View source for Black Sea

{{Short description|Eurasian sea northeast of the Mediterranean}}
{{About|the large body of water}}
{{redirect|Euxine|the town of ancient Caria|Euxine (Caria)}}
{{Use American English|date=January 2025}}
{{Use dmy dates|date=November 2019}}
{{Infobox body of water
| name               = Black Sea
| image              = Black Sea map.png
| alt                = location map
| caption            = The location of the Black Sea
| image_bathymetry   = Map of the Black Sea with bathymetry and surrounding relief.svg
| caption_bathymetry = Map of the Black Sea with [[bathymetry]] and surrounding relief
| location           = [[Eastern Europe]] and [[West Asia]]
| coords             = {{Coordinates|44|N|35|E|type:waterbody_scale:8000000 |display=inline,title}}
| type               = [[Sea]]
| inflow             = [[Sea of Marmara]], [[Sea of Azov]], [[Danube]], [[Dnieper]], [[Don (river)|Don]], [[Dniester]], [[Kuban (river)|Kuban]], [[Black Sea undersea river]] (through the [[Bosphorus Strait]])
| outflow            = [[Bosporus]], [[Kerch Strait]]
| catchment          = 
| basin_countries    = * {{flag|Bulgaria}}
* {{flag|Georgia}}
* {{flag|Romania}}
* {{flag|Russia}}
* {{flag|Turkey}}
* {{flag|Ukraine}}

Partially recognised states:
* {{flag|Abkhazia}}{{efn|name=Abkhazia| {{Abkhazia-note}}}}
<br />A large number of countries included in [[drainage basin]]s for inflow rivers
| length             = {{convert|1175|km|mi|0|abbr=on}}
| width              = 
| area               = {{convert|436400|km2|sqmi||abbr=on}}
| max-depth          = {{convert|2212|m|ft|0|abbr=on}}
| depth              = {{convert|1253|m|ft|0|abbr=on}}
| volume             = {{convert|547000|km3|cumi|-2|abbr=on}}
| residence_time     = 
| shore              = 
| elevation          = 
| frozen             = 
| islands            = [[:Category:Islands of the Black Sea|10+]]
| islands_category   = Islands of the Black Sea
| cities             = 
| reference          = 
}}
[[File:Veleka-sinemorets-mouth-dinev.jpg|thumb|upright=1.35|The estuary of the [[Veleka]] in the Black Sea. [[Longshore drift]] has deposited [[sediment]] along the [[shoreline]] which has led to the formation of a [[spit (landform)|spit]] ([[Sinemorets]], Bulgaria).]] [[File:Black Sea coast of Georgia (country), with skyline of Batumi on the horizon.jpg|thumb|right|upright=1.35| Black Sea coast of western [[Georgia (country)|Georgia]], with the skyline of [[Batumi]] on the horizon]]
[[File:Ласточкино гнездо.jpg|thumb|upright=1.35| [[Swallow's Nest]] in [[Crimea]]]]
[[File:Amisos_Tepesi'nden_Amazon_Adası'na_bakış.JPG|thumb|upright=1.35|Coastline of [[Samsun]] in [[Turkey]]]]
[[File:Санаторий Орджоникидзе (г.Сочи) 01.jpg|thumb|upright=1.35|A [[Sanatorium (resort)|sanatorium]] in [[Sochi]], Russia]]

The '''Black Sea''' is a [[marginal sea]] lying between [[Europe]] and [[Asia]], east of the [[Balkans]], south of the [[East European Plain]], west of the [[Caucasus]], and north of [[Anatolia]]. It is bounded by [[Bulgaria]], [[Georgia (country)|Georgia]], [[Romania]], [[Russia]], [[Turkey]], and [[Ukraine]]. The Black Sea is [[Inflow (hydrology)|supplied by]] major rivers, principally the [[Danube]], [[Dnieper]] and [[Dniester]]. Consequently, while six countries have a coastline on the sea, its [[drainage basin]] includes parts of 24 countries in Europe.<ref>{{cite web| url = http://blacksea-education.ru/e2.shtml| title = "Black Sea Geography, Oceanography, Ecology, History"| access-date = 18 February 2018| archive-date = 22 February 2018| archive-url = https://web.archive.org/web/20180222094304/http://blacksea-education.ru/e2.shtml}} ''Living Black Sea''</ref>

The Black Sea, not including the [[Sea of Azov]], covers {{convert|436400|km2|abbr=on}},<ref>{{cite web|title= Black Sea Geography |work= University of Delaware College of Marine Studies |url= https://www.ceoe.udel.edu/blacksea/geography/index.html |year= 2003|access-date= 3 April 2014 |archive-url= https://web.archive.org/web/20140407065633/https://www.ceoe.udel.edu/blacksea/geography/index.html |archive-date=7 April 2014}}</ref> has a maximum depth of {{convert|2212|m|abbr= on}},<ref>Maximum depth—{{cite web |title= Europa – Gateway of the European Union website |work= Environment and Enlargement – The Black Sea: Facts and Figures |url= http://ec.europa.eu/environment/enlarg/blackseafactsfigures_en.htm |archive-url= https://web.archive.org/web/20081114143619/http://ec.europa.eu/environment/enlarg/blackseafactsfigures_en.htm|archive-date= 14 November 2008}}</ref> and a volume of {{Convert|547000|km3|abbr= on}}.<ref>{{cite journal |title= Unexpected changes in the oxic/anoxic interface in the Black Sea |journal= Nature|date= 30 March 1989|volume= 338 |issue= 6214 |doi= 10.1038/338411a0 |pages= 411–413|last1= Murray |first1= J. W. |last2= Jannasch |first2= H. W. |last3= Honjo |first3= S |last4= Anderson |first4= R. F. |last5= Reeburgh |first5= W. S. |last6= Top |first6= Z. |last7= Friederich |first7= G. E. |last8= Codispoti |first8= L. A. |last9= Izdar |first9= E. |bibcode= 1989Natur.338..411M |s2cid= 4306135|url= https://escholarship.org/uc/item/7xg3p017}}</ref>
Most of its coasts ascend rapidly.
These rises are the [[Pontic Mountains]] to the south, bar the southwest-facing peninsulas, the [[Caucasus Mountains]] to the east, and the [[Crimean Mountains]] to the mid-north.
In the west, the coast is generally small [[floodplain]]s below foothills such as the [[Strandzha]]; [[Cape Emine]], a dwindling of the east end of the [[Balkan Mountains]]; and the [[Dobruja Plateau]] considerably farther north. The longest east–west extent is about {{convert|1175|km|abbr= on}}.<ref>{{Cite book |url=https://archive.org/details/worlditspeoplese0010unse |url-access=registration |page=[https://archive.org/details/worlditspeoplese0010unse/page/n151 1444] |quote=Black Sea 1175 km east west. |title=World and Its Peoples |date=21 July 2010 |publisher=Marshall Cavendish |via=Internet Archive |isbn=978-0-7614-7902-4}}</ref> Important cities along the coast include (clockwise from the [[Bosporus]]) the northern suburbs of [[Istanbul]], [[Burgas]], [[Varna, Bulgaria|Varna]], [[Constanța]], [[Odesa]], [[Yalta]], [[Kerch]], [[Yevpatoria]], [[Sevastopol]], [[Novorossiysk]], [[Sochi]], [[Poti]], [[Batumi]], [[Rize]], [[Trabzon]], [[Ordu]], [[Simferopol]], [[Samsun]] and [[Zonguldak]].<ref name="telegraph.co.uk">{{Cite web |date=2010-08-02 |title=Undersea river discovered flowing on sea bed - Telegraph |url=http://www.telegraph.co.uk/earth/environment/7920006/Undersea-river-discovered-flowing-on-sea-bed.html |access-date=2024-12-28 |archive-url=https://web.archive.org/web/20100802165402/http://www.telegraph.co.uk/earth/environment/7920006/Undersea-river-discovered-flowing-on-sea-bed.html |archive-date=2 August 2010 }}</ref>

The Black Sea has a positive [[water balance]], with an annual net outflow of {{convert|300|km3|abbr= on}} per year through the Bosporus and the [[Dardanelles]] into the [[Aegean Sea]].<ref>{{Cite journal |last1=Miladinova |first1=S. |last2=Stips |first2=A. |last3=Garcia-Gorriz |first3=E. |last4=Macias Moy |first4=D. |date=July 2017 |title=Black Sea thermohaline properties: Long-term trends and variations |journal= Journal of Geophysical Research: Oceans|volume=122 |issue=7 |pages=5624–5644 |doi=10.1002/2016JC012644 |issn=2169-9275 |pmc=5606501 |pmid=28989833|bibcode=2017JGRC..122.5624M }}</ref> While the net flow of water through the Bosporus and Dardanelles (known collectively as the [[Turkish Straits]]) is out of the Black Sea, water generally flows in both directions simultaneously: Denser, more [[saline water]] from the Aegean flows into the Black Sea underneath the less dense, fresher water that flows out of the Black Sea. This creates a significant and permanent layer of deep water that does not drain or mix and is therefore [[Anoxic waters|anoxic]]. This anoxic layer is responsible for the preservation of [[Ancient Black Sea shipwrecks|ancient shipwrecks]] which have been found in the Black Sea, which ultimately drains into the [[Atlantic Ocean]], via the Turkish Straits and the Aegean Sea into the [[Mediterranean Sea]], and from it to the Atlantic proper through the Strait of Gibraltar. The Bosporus strait connects it to the small [[Sea of Marmara]] which in turn is connected to the Aegean Sea via the strait of the [[Dardanelles]]. To the north, the Black Sea is connected to the Sea of Azov by the [[Kerch Strait]].

The water level has varied significantly over geological time. Due to these variations in the water level in the basin, the surrounding [[continental shelf|shelf]] and associated aprons have sometimes been dry land. At certain critical water levels, connections with surrounding water bodies can become established. It is through the most active of these connective routes, the Turkish Straits, that the Black Sea joins the [[world ocean|World Ocean]]. During geological periods when this hydrological link was not present, the Black Sea was an [[endorheic basin]], operating independently of the global ocean system (similar to the [[Caspian Sea]] today). Currently, the Black Sea water level is relatively high; thus, water is being exchanged with the Mediterranean. The [[Black Sea undersea river]] is a current of particularly saline water flowing through the Bosporus Strait and along the [[seabed]] of the Black Sea, the first of its kind discovered.<ref name="telegraph.co.uk"/>

== Name ==
[[File:OrduSeaside.jpg|thumb|Coast of the Black Sea at [[Ordu]]]]
[[File:View to the Kapchik Cape in Crimea (2).jpg|thumb|Kapchik Cape in Crimea]]
[[File:The Black Sea near Constanţa, Romania.JPG|thumb|The Black Sea near [[Constanța]], Romania]]
[[File:Burgas Bridge, Бургаският мост.jpg|thumb|Coast of the Black Sea at [[Burgas]]]]

=== Modern names ===
Current names of the sea are usually equivalents of the English name "Black Sea", including these given in the countries bordering the sea:<ref>{{cite book|author=Özhan Öztürk|url=http://www.karalahana.com/makaleler/karadeniz/karadeniz-ozhan-ozturk.htm|title=Karadeniz Ansiklopedik Sözlük|publisher=Heyamola Yayınları|year=2005|place=İstanbul|pages=617–620|archive-url=https://web.archive.org/web/20121015182227/http://www.karalahana.com/makaleler/karadeniz/karadeniz-ozhan-ozturk.htm|archive-date=15 October 2012}}</ref>
* {{langx|ab|Амшын Еиқәа|translit=Amŝən Ejkʷa}}, {{IPA|ab|ɑmʂɨn ɛjkʷʰɑ|IPA}}
* {{langx|ady|Хы Шӏуцӏэ|translit=Xə Šʷʼucʼɛ}}, {{IPA|ady|xɘ ʃʷʼtsʼɜ|IPA}}
* {{langx|hy|Սեւ ծով|translit=Sev cov}}, {{IPA|hy|sɛv t͡sɔv|IPA|audio=}}
* {{langx|az|Qara dəniz}}, {{IPA|az|ɡɑˈɾɑ dæˈniz|IPA}}
* {{langx|bg|Чeрно морe|translit=Čérno moré}}, {{IPA|bg|ˈt͡ʃɛrno moˈrɛ|IPA}}
* {{crh|Qara deñiz|Къара денъиз}}, {{IPA|crh|qɑrɑ deŋiz|IPA}}
* {{langx|gag|Kara deniz}}
* {{langx|ka|შავი ზღვა|translit=Shavi Zghva}}, {{IPA|ka|ʃavi zʁʷa|IPA}}
* [[Laz language|Laz]] and {{langx|xmf|უჩა ზუღა|translit=Ucha Zugha}}, {{IPA|xmf|ˈutʃä ˈzuɣä|IPA}}, or simply {{lang|xmf|ზუღა}}, {{Transliteration|xmf|Zugha}}, {{IPA|xmf|ˈzuɣä|IPA}}, "Sea"
* {{langx|fa|دریای سیاه|translit=daryā-ye siyāh}}
* {{langx|ro|Marea Neagră}}, {{IPA|ro|ˈmare̯a ˈne̯aɡrə|pron|Ro-Marea Neagră.ogg}}
* {{langx|ru|Чёрное мо́ре|Čórnoje móre}}, {{IPA|ru|ˈtɕɵrnəjɪ ˈmorʲɪ|IPA}}
* {{langx|tr|Karadeniz}}, {{IPA|tr|kaˈɾadeniz|IPA}}
* {{langx|uk|Чо́рне мо́ре|translit=Čórne móre}}, {{IPA|uk|ˈtʃɔrne ˈmɔre|IPA}}

Such names have not yet been shown conclusively to predate the 13th{{spaces}}century.{{sfn|Schmitt|1989|pages=310–313}}

In [[Greece]], the historical name "Euxine Sea", which holds a different literal meaning (see below), is still widely used:
* {{langx|el|Εύξεινος Πόντος|translit=Éfxinos Póndos|lit=Hospitable Sea}}, {{IPA|el|ˈefksinos ˈpondos|}}; the name {{langx|el|Μαύρη Θάλασσα|Mávri Thálassa|Black Sea|label=none}}, {{IPA|el|ˈmavɾi ˈθalasa|}}, is used, but is much less common.{{citation needed|date=September 2021}}

The Black Sea is one of four seas named in English after common [[color term]]s – the others being the [[Red Sea]], the [[White Sea]] and the [[Yellow Sea]].

=== Historical names and etymology ===
The earliest known name of the Black Sea is the Sea of Zalpa, so called by both the [[Hattians]]<ref>The Journal of Indo-European Studies, p.79. United States, n.p, 1985. [https://books.google.com/books?id=QaMYAAAAYAAJ Google Books]</ref> and their conquerors, the [[Hittites]]. The Hattic city of [[Zalpuwa|Zalpa]] was "situated probably at or near the estuary of the Marrassantiya River, the modern [[Kızılırmak River|Kızıl Irmak]], on the Black Sea coast."<ref>Burney, Charles. Historical Dictionary of the Hittites, p.333. United States, Rowman & Littlefield Publishers, 2018. [https://books.google.com/books?id=YRhbDwAAQBAJ Google Books]. Accessed 26 February 2024.</ref>

The principal [[Greek language|Greek]] name ''Póntos Áxeinos'' is generally accepted to be a rendering of the [[Iranian languages|Iranian]] word {{lang|ira|*axšaina-}} ("dark colored").{{sfn|Schmitt|1989|pages=310–313}} Ancient Greek voyagers adopted the name as {{lang|grc-Latn|Á-xe(i)nos}}, identified with the Greek word {{lang|grc-Latn|áxeinos}} (inhospitable).{{sfn|Schmitt|1989|pages=310–313}} The name {{lang|grc|Πόντος Ἄξεινος}} {{transliteration|grc|ISO|''Póntos Áxeinos''}} (Inhospitable Sea), first attested in [[Pindar]] ({{c.|475 BC}}), was considered an ill omen and was euphemized to its opposite, {{lang|grc|Εὔξεινος Πόντος}} {{transliteration|grc|ISO|''Eúxeinos Póntos''}} (Hospitable Sea), also first attested in Pindar. This became the commonly used designation in Greek, although in mythological contexts the "true" name {{lang|grc-Latn|Póntos Áxeinos}} remained favored.{{sfn|Schmitt|1989|pages=310–313}}

[[Strabo]]'s ''[[Geographica]]'' (1.2.10) reports that in antiquity, the Black Sea was often simply called "the Sea" ({{lang|grc|ὁ πόντος}} {{transliteration|grc|ISO|''ho Pontos''}}).<ref name="Geographica vol.I">{{cite book|url=https://penelope.uchicago.edu/Thayer/e/roman/texts/strabo/home.html|title=Strabo: Geography, Volume I: Books 1–2|date=1917|publisher=Harvard University Press|editor1-last=Jones|editor1-first=Horace Leonard|location=Cambridge, MA|access-date=26 November 2021}}</ref> He thought that the sea was called the "Inhospitable Sea" {{lang|grc|Πόντος Ἄξεινος}} {{transliteration|grc|ISO|''Póntos Áxeinos''}} by the inhabitants of the [[Pontus (region)|Pontus]] region of the southern shoreline before Greek colonization due to its difficult navigation and hostile barbarian natives (7.3.6), and that the name was changed to "hospitable" after the [[Milesians (Greek)|Milesians]] [[Greek colonisation|colonized]] the region, bringing it into the Greek world.<ref name="Geographica vol.III">{{cite book|url=https://penelope.uchicago.edu/Thayer/e/roman/texts/strabo/home.html|title=Strabo: Geography, Volume III: Books 6–7|date=1924|publisher=Harvard University Press|editor1-last=Jones|editor1-first=Horace Leonard|location=Cambridge, MA|access-date=26 November 2021}}</ref>

Popular supposition derives "Black Sea" from the dark color of the water or climatic conditions. Some scholars understand the name to be derived from a system of [[Cardinal direction#Cultural variations|color symbolism representing the cardinal directions]], with black or dark for north, red for south, white for west, and green or light blue for east.{{sfn|Schmitt|1989|pages=310–313}} Hence, "Black Sea" meant "Northern Sea". According to this scheme, the name could only have originated with a people living between the northern (black) and southern [[Red Sea|(red) sea]]s: this points to the [[Achaemenid Empire|Achaemenids]] (550–330 BC).{{sfn|Schmitt|1989|pages=310–313}} This interpretation has been labeled as [[folk etymology]]<ref>Karatay, Osman. (2011). "On the origins of the name for the 'Black Sea'." Journal of Historical Geography, Volume 37, Issue 1, Pages 1–11.</ref> and may reflect a primitive historical understanding of the "P/Bla" [[phoneme]] originally associated with the name.<ref name="Beekes">Beekes, R. S. P. (2002). "The Origin of the Etruscans." Koninklijke Nederlandse Akademie van Wetenschappen,Amsterdam. [https://www.robertbeekes.nl/wp-content/uploads/2019/08/b110.pdf Robert Beekes]</ref>

In the [[Bundahishn|Greater Bundahishn]], a [[Middle Persian]] [[Zoroastrianism|Zoroastrian]] scripture, the Black Sea is called {{lang|pal-Latn|Siyābun}}.<ref>{{Cite web|last=Peterson|first=Joseph H.|title=Greater Bundahishn|url=http://www.avesta.org/mp/grb1.htm#chap8|access-date=1 July 2017|website=www.avesta.org}}</ref> In the tenth-century Persian geography book {{lang|fa-Latn|[[Hudud al-'Alam]]|italic=yes}}, the Black Sea is called ''Georgian Sea'' ({{lang|fa-Latn|daryā-yi Gurz}}).<ref>[http://www.kroraina.com/hudud/hud_42.html § 42. Discourse on the Country of Rūm, its Provinces and Towns] {{Webarchive|url=https://web.archive.org/web/20210225152115/http://www.kroraina.com/hudud/hud_42.html |date=25 February 2021 }} Hudud al-'Alam</ref> ''[[The Georgian Chronicles]]'' use the name {{lang|oge-Latn|zğua sperisa}} {{lang|oge|ზღუა სპერისა}} (Sea of Speri) after the [[Kartvelian peoples|Kartvelian]] tribe of Speris or [[Saspers]].<ref>[http://titus.uni-frankfurt.de/texte/etcs/cauc/ageo/kcx1/kcx1.htm?kcx1002.htm Part II] {{Webarchive|url=https://web.archive.org/web/20200628200934/http://titus.uni-frankfurt.de/texte/etcs/cauc/ageo/kcx1/kcx1.htm?kcx1002.htm |date=28 June 2020 }} Georgian Chronicles, Line of ed: 14</ref> Other modern names such as {{lang|ru-Latn|Chyornoye more}} and {{lang|tr|Karadeniz}} (both meaning Black Sea) originated during the 13th century.{{sfn|Schmitt|1989|pages=310–313}} A 1570 map {{lang|la|Asiae Nova Descriptio|italic=yes}} from [[Abraham Ortelius]]'s {{lang|la|[[Theatrum Orbis Terrarum]]}} labels the sea {{lang|la|Mar Maggior}} (Great Sea), compare Latin {{lang|la|Mare major}}.<ref>{{Cite web|title=Central Asia and Dravidan Connection – Revealed – Part 6|url=http://drannadurai.com/His_Central%20Asia%20and%20Dravidan%20Connection%20-%20Revealed%20-%20Part%206.htm|access-date=15 June 2020}}</ref>

English writers of the 18th century often used ''Euxine Sea'' ({{IPAc-en|ˈ|j|uː|k|s|ᵻ|n}} or {{IPAc-en|ˈ|j|uː|k|ˌ|s|aɪ|n}}).<ref>{{cite book|last=Gibbon|first=Edward|title=The History of the Decline and Fall of the Roman Empire|publisher=Everyman's Library|year=1993|isbn=0-679-42308-7|orig-date=1910}}</ref> During the [[Ottoman Empire]], it was called either {{lang|ota-Latn|Bahr-i Siyah}} ([[Perso-Arabic]]) or {{lang|ota-Latn|Karadeniz}} ([[Ottoman Turkish]]), both meaning "Black Sea".<ref>{{Cite web |date=2025-03-11 |title=Black Sea {{!}} Location, Region, Map, Countries, & Facts {{!}} Britannica |url=https://www.britannica.com/place/Black-Sea |access-date=2025-03-13 |website=www.britannica.com |language=en}}</ref>

== Geography ==
The [[International Hydrographic Organization]] defines the limits of the Black Sea as follows:<ref>{{cite web|url=https://iho.int/uploads/user/pubs/standards/s-23/S-23_Ed3_1953_EN.pdf|title=Limits of Oceans and Seas, 3rd edition|year=1953|publisher=International Hydrographic Organization|access-date=28 December 2020|archive-url=https://web.archive.org/web/20111008191433/http://www.iho.int/iho_pubs/standard/S-23/S-23_Ed3_1953_EN.pdf|archive-date=8 October 2011}}</ref>

{{blockquote|''On the Southwest.'' The Northeastern limit of the [[Sea of Marmara]] [A line joining [[Cape Rumili]] with [[Cape Anatoli]] (41°13'N)].

''In the [[Kerch Strait|Kertch Strait]].'' A line joining Cape Takil and Cape Panaghia (45°02'N).}}The area surrounding the Black Sea is commonly referred to as the ''Black Sea Region''. Its northern part lies within the ''[[Chernozem]] belt'' (black soil belt) which goes from eastern Croatia ([[Slavonia]]), along the [[Danube]] (northern Serbia, northern Bulgaria ([[Danubian Plain (Bulgaria)|Danubian Plain]]) and southern Romania ([[Wallachian Plain]]) to northeast Ukraine and further across the [[Central Black Earth Region]] and southern Russia into [[Siberia]].<ref>{{cite web|title=Agriculture in the Black Sea Region|url=http://bs-agro.com/index.php/about-us|archive-url=https://web.archive.org/web/20131031072227/http://bs-agro.com/index.php/about-us|archive-date=31 October 2013|access-date=14 January 2014|url-status=usurped|publisher=Bs-agro.com}}</ref>

The [[littoral zone]] of the Black Sea is often referred to as the '''Pontic littoral''' or '''Pontic zone'''.<ref name="Prothero1">{{cite book|last=Prothero|first=G.W.|url=http://www.wdl.org/en/item/11766/view/1/17/|title=Anatolia|publisher=H.M. Stationery Office|year=1920|location=London}}</ref>

The largest [[bay]]s of the Black Sea are [[Karkinit Bay]] in Ukraine; the [[Gulf of Burgas]] in Bulgaria; [[Dnieper-Bug Estuary|Dnieprovska Gulf]] and [[Dniester Estuary|Dniestrovsky]] [[Liman (landform)|Liman]], both in Ukraine; and [[Hamsilos Bay|Sinop Bay]] and [[Samsun]] Bay, both in Turkey.<ref name="bsnn.org">{{Cite web |url= https://www.bsnn.org/black_sea.html |title=Our Black Sea |website=www.bsnn.org |publisher=Black Sea NGO Network}}</ref>

=== Coastline and exclusive economic zones ===
<!-- Possibly some text about [[exclusive economic zone]]s in Black Sea (including [[Sea of Azov]]). Possibly some text about [[coastline length]] in Black Sea (including Sea of Azov) -->{| class="wikitable sortable" style="text-align:right;"
|+ Coastline length and area of exclusive economic zones
|-
! scope="col" | Country
! scope="col" | [[Coastline length]] (km)<ref name="bsnn.org" />
! scope="col" | [[Exclusive economic zone]]s area (km<sup>2</sup>)<ref>{{cite web |title=Sea Around Us {{!}} Fisheries, Ecosystems and Biodiversity |url=http://www.seaaroundus.org/data/#/eez |publisher=University of British Columbia}}</ref>
|-
! scope="row" | {{TUR}}
| 1,329
| 172,484
|-
! scope="row" | {{UKR}}
| 2,782
| 132,414
|-
! scope="row" | {{RUS}}
| 800
| 67,351
|-
! scope="row" | {{BGR}}
| 354
| 35,132
|-
! scope="row" | {{GEO}}
| 310 (without Abkhazia{{efn|name=Abkhazia}} 100<ref name="Proletarskaya Gazeta">{{cite web |author= Aleksey Danko |url= http://www.revolutionarydemocracy.org/rdv14n2/pgossetia.htm | title= The Class Roots and Sources of the Aggressive Actions of Georgia Against South Ossetia and Abkhazia and the Aggravation of the Situation in the Caucasus |publisher= Proletarskaya Gazeta #30 |date=November 2008 |access-date= 2 October 2012 |quote= Moreover, the Abkhazian coast stretches 200 kilometres, which has the potential to significantly increase the influence of either Russia or Georgia on the Black sea, including their military presence.}}</ref>)
| 22,947
|-
! scope="row" | {{ROU}}
| 225
| 29,756
|-
! scope="row" | {{Flag|Abkhazia}}{{efn|name=Abkhazia}}
| 210<ref name="Proletarskaya Gazeta"/>
| –
|- class="sortbottom" style="background:#9acdff;"
! scope="row" | Total
| style="background:#9acdff; font-weight:bold;" | 5,800
| style="background:#9acdff; font-weight:bold;" | 460,084
|}

=== Drainage basin ===
{{Main|Organization of the Black Sea Economic Cooperation}}

The largest [[river]]s flowing into the Black Sea are:<ref name="bsnn.org" />

{{Div col |colwidth=10em}}
# [[Danube]]
# [[Dnieper]]
# [[Don (river)|Don]]
# [[Dniester]]
# [[Kızılırmak River|Kızılırmak]]
# [[Kuban (river)|Kuban]]
# [[Sakarya River|Sakarya]]
# [[Southern Bug]]
# [[Çoruh|Çoruh/Chorokhi]]
# [[Yeşilırmak (river)|Yeşilırmak]]
# [[Rioni]]
# [[Yeya]]
# [[Mius]]
# [[Kamchiya]]
# [[Enguri|Enguri/Egry]]
# [[Kalmius]]
# [[Molochna]]
# [[Tylihul (river)|Tylihul]]
# [[Velykyi Kuialnyk]]
# [[Veleka]]
# [[Rezovo (river)|Rezovo]]
# [[Kodori (river)|Kodori/Kwydry]]
# [[Bzyb (river)|Bzyb/Bzipi]]
# [[Supsa (river)|Supsa]]
# [[Mzymta]]
{{Div col end}}

These rivers and their tributaries comprise a {{Convert|2|e6km2||abbr=unit|adj=on}} Black Sea drainage basin that covers wholly or partially 24 countries:<ref>{{Cite web|url=http://www.blacksea-commission.org/_publ-ML-CH1.asp|title=Marine Litter Report|website=www.blacksea-commission.org}}</ref><ref>{{Cite journal|doi = 10.1080/14683850500122943|title = Europe's new region: The Black Sea in the wider Europe neighbourhood|year = 2005 |last = Aydin|first = Mustafa|journal = Southeast European and Black Sea Studies|volume = 5|issue = 2|pages = 257–283|s2cid = 154395443}}</ref><ref>{{Cite web|url=https://blacksea-cbc.net/overview/|title=Black Sea|access-date=7 September 2020|archive-date=7 September 2020|archive-url=https://web.archive.org/web/20200907151235/https://blacksea-cbc.net/overview/}}</ref><ref>{{Cite web|url=http://www.oceansatlas.org/subtopic/en/c/922/|title=UN Atlas of the Oceans: Subtopic|website=www.oceansatlas.org}}</ref><ref>{{cite web| url = http://www.fao.org/fileadmin/user_upload/oceanatlas/img/1132587048006_BSBasinPolitical.gif| title = The Black Sea Basin}}</ref>

{{div col|colwidth=16em}}
* {{ALB}}
* {{AUT}}
* {{BLR}}
* {{BIH}}
* {{BGR}}
* {{HRV}}
* {{CZE}}
* {{GEO}}
* {{GER}}
* {{GRE}}
* {{HUN}}
* {{ITA}}
* {{MNE}}
* {{MDA}}
* {{MKD}}
* {{POL}}
* {{ROM}}
* {{RUS}}
* {{SRB}}
* {{SVK}}
* {{SLO}}
* {{SUI}}
* {{TUR}}
* {{UKR}}
Unrecognized states:
* {{flag|Abkhazia}}{{efn|name=Abkhazia}}
{{div col end}}

=== Islands ===
{{main|List of islands in the Black Sea}}Some islands in the Black Sea belong to Bulgaria, Romania, Turkey, and Ukraine:

{{Div col|colwidth=30em}}
* St. Thomas Island – Bulgaria
* [[St. Anastasia Island]] – Bulgaria
* St. Cyricus Island – Bulgaria
* St. Ivan Island – Bulgaria
* St. Peter Island – Bulgaria
* Sacalinu Mare Island – Romania
* Sacalinu Mic Island – Romania
* [[K Island]] – Romania and Ukraine
* Utrish Island
* Krupinin Island
* Sudiuk Island
* Kefken Island
* Oreke Island
* Giresun Island – Turkey
* [[Dzharylhach|Dzharylhach Island]] – Ukraine
* [[Snake Island (Black Sea)|Zmiinyi (Snake) Island]] – Ukraine
{{Div col end}}

=== Climate ===
[[File:Ice on the Gulf of Odessa.jpg|thumb|Ice on the [[Gulf of Odesa]]]]
Short-term climatic variation in the Black Sea region is significantly influenced by the operation of the [[North Atlantic oscillation]], the climatic mechanisms resulting from the interaction between the north Atlantic and mid-latitude air masses.<ref>{{cite journal|last1=Hurrell|first1=J. W.|year=1995|title=Decadal Trends in the North Atlantic Oscillation: Regional Temperatures and Precipitation|journal=Science|volume=269|issue=5224|pages=676–679|bibcode=1995Sci...269..676H|doi=10.1126/science.269.5224.676|pmid=17758812|s2cid=23769140}}</ref> While the exact mechanisms causing the North Atlantic Oscillation remain unclear,<ref>{{cite journal|last1=Lamy|first1=F.|last2=Arz|first2=H. W.|last3=Bond|first3=G. C.|last4=Barh|first4=A.|last5=Pätzold|first5=J.|year=2006|title=Multicentennial-scale hydrological changes in the Black Sea and northern Red Sea during the Holocene and the Arctic/North Atlantic Oscillation|journal=Paleoceanography|volume=21|issue=1|article-number=2005PA001184 |pages=n/a|bibcode=2006PalOc..21.1008L|doi=10.1029/2005PA001184|doi-access=free}}</ref> it is thought the climate conditions established in western Europe mediate the heat and precipitation fluxes reaching Central Europe and Eurasia, regulating the formation of winter [[cyclone]]s, which are largely responsible for regional [[precipitation]] inputs<ref>{{cite journal|last1=Türkeş|first1=Murat|year=1996|title=Spatial and temporal analysis of annual rainfall variations in Turkey|journal=International Journal of Climatology|volume=16|issue=9|pages=1057–1076|bibcode=1996IJCli..16.1057T|doi=10.1002/(SICI)1097-0088(199609)16:9<1057::AID-JOC75>3.3.CO;2-4}}</ref> and influence Mediterranean [[sea surface temperature]]s (SSTs).<ref>{{cite journal|author=Cullen, H. M.|author2=A. Kaplan|display-authors=etal|year=2002|title=Impact of the North Atlantic Oscillation on Middle Eastern climate and streamflow|url=http://rainbow.ldeo.columbia.edu/~alexeyk/Papers/Cullen_etal02.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://rainbow.ldeo.columbia.edu/~alexeyk/Papers/Cullen_etal02.pdf |archive-date=9 October 2022 |url-status=live|journal=Climatic Change|volume=55|issue=3|pages=315–338|doi=10.1023/A:1020518305517|bibcode=2002ClCh...55..315C |s2cid=13472363}}</ref>

The relative strength of these systems also limits the amount of cold air arriving from northern regions during winter.<ref>{{cite journal|author1=Ozsoy, E.|author2=U. Unluata|name-list-style=amp|year=1997|title=Oceanography of the Black Sea: A review of some recent results|journal=Earth-Science Reviews|volume=42|issue=4|pages=231–272|bibcode=1997ESRv...42..231O|doi=10.1016/S0012-8252(97)81859-4|hdl=11511/65646|hdl-access=free}}</ref> Other influencing factors include the regional [[topography]], as depressions and storm systems arriving from the [[Mediterranean]] are funneled through the low land around the Bosporus, with the [[Pontic Mountains|Pontic]] and [[Caucasus Mountains|Caucasus]] mountain ranges acting as waveguides, limiting the speed and paths of cyclones passing through the region.<ref>Brody, L. R., Nestor, M.J.R. (1980). [http://www.nrlmry.navy.mil/forecaster_handbooks/Med_2/Handbook%20for%20Forecasters%20in%20the%20Mediterrean%20Pt2%20Cover%20Page.pdf Regional Forecasting Aids for the Mediterranean Basin] {{Webarchive|url=https://web.archive.org/web/20111126045318/http://www.nrlmry.navy.mil/forecaster_handbooks/Med_2/Handbook%20for%20Forecasters%20in%20the%20Mediterrean%20Pt2%20Cover%20Page.pdf |date=26 November 2011 }}. ''Handbook for Forecasters in the Mediterranean'', Naval Research Laboratory. Part 2.</ref>

== Geology and bathymetry ==
[[File:Судак.jpg|thumb|The bay of [[Sudak]], Crimea]]
The Black Sea is divided into two depositional basins—the Western Black Sea and Eastern Black Sea—separated by the Mid-Black Sea High, which includes the Andrusov Ridge, Tetyaev High, and Archangelsky High, extending south from the [[Crimea|Crimean Peninsula]]. The basin includes two distinct relict [[back-arc basin]]s which were initiated by the splitting of an [[Albian]] [[volcanic arc]] and the [[subduction]] of both the [[Paleo-Tethys Ocean|Paleo]]- and Neo-[[Tethys Ocean|Tethys]] oceans, but the timings of these events remain uncertain. Arc volcanism and extension occurred as the Neo-Tethys Ocean subducted under the southern margin of [[Laurasia]] during the [[Mesozoic]]. Uplift and compressional deformation took place as the Neotethys continued to close. Seismic surveys indicate that rifting began in the Western Black Sea in the [[Barremian]] and [[Aptian]] followed by the formation of oceanic crust 20{{spaces}}million years later in the [[Santonian]].<ref>{{cite book |title=Petroleum Geology of the Black Sea |year=2018 |publisher=The Geological Society of London |url=https://books.google.com/books?id=1q5oDwAAQBAJ&q=geology+black+sea |page=2 |editor1-last=Simmons |editor1-first=M. D. |editor2-last=Tari |editor2-first=G. C. |editor3-last=Okay |editor3-first=A. I. |isbn=978-1-78620-358-8}}</ref><ref>{{cite journal |pmid=16057188 |year=1970 |last1=McKenzie |first1=DP |title=Plate tectonics of the Mediterranean region |volume=226 |issue=5242 |pages=239–43 |doi=10.1038/226239a0 |journal=Nature |bibcode=1970Natur.226..239M |s2cid=2991363}}</ref><ref>{{cite journal |author=McClusky, S. |author2=S. Balassanian |year=2000 |title=Global Positioning System constraints on plate kinematics and dynamics in the eastern Mediterranean and Caucasus |journal= Journal of Geophysical Research: Solid Earth|volume=105 |issue=B3 |pages=5695–5719 |url=http://www.ipgp.fr/~armijo/paraseminario/McClusky2000.pdf |archive-url=https://web.archive.org/web/20120308202329/http://www.ipgp.fr/~armijo/paraseminario/McClusky2000.pdf |archive-date=8 March 2012 |url-status=live |bibcode=2000JGR...105.5695M |doi=10.1029/1999JB900351 |display-authors=etal |doi-access=free}}</ref> Since its initiation, compressional tectonic environments led to [[subsidence]] in the basin, interspersed with extensional phases resulting in large-scale [[volcanism]] and numerous [[orogeny|orogenies]], causing the uplift of the [[Greater Caucasus]], [[Pontides]], southern [[Crimea|Crimean Peninsula]] and [[Balkan]]ides mountain ranges.<ref name="ReferenceA">{{cite journal |doi=10.1016/j.epsl.2007.10.033 |title=Cenozoic evolution of the eastern Black Sea: A test of depth-dependent stretching models |year=2008 |last1=Shillington |first1=Donna J. |last2=White |first2=Nicky |last3=Minshull |first3=Timothy A. |last4=Edwards |first4=Glyn R.H. |last5=Jones |first5=Stephen M. |last6=Edwards |first6=Rosemary A. |last7=Scott |first7=Caroline L. |journal=Earth and Planetary Science Letters |volume=265 |issue=3–4 |pages=360–378 |bibcode=2008E&PSL.265..360S |url=http://nora.nerc.ac.uk/141393/1/epsl_djs_rev2_final_lowres.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://nora.nerc.ac.uk/141393/1/epsl_djs_rev2_final_lowres.pdf |archive-date=9 October 2022 |url-status=live}}</ref>

[[File:Yavuz-Sultan-Selim-Brücke.jpg|thumb|The [[Yavuz Sultan Selim Bridge]] in [[Istanbul]], Turkey, crosses the [[Bosporus]] strait near its entrance to the Black Sea. Connecting Europe and Asia, it is one of the tallest suspension bridges in the world.]]
During the [[Messinian salinity crisis]] in the neighboring [[Mediterranean Sea]], water levels fell but without drying up the sea.{{sfn|Simmons|Tari|Okay|2018|p=11}} The collision between the [[Eurasian Plate|Eurasian]] and [[African Plate|African]] plates and the westward escape of the [[Anatolian Plate|Anatolian]] block along the [[North Anatolian Fault|North Anatolian]] and [[East Anatolian Fault|East Anatolian]] faults dictates the current tectonic regime,<ref name="ReferenceA"/> which features enhanced subsidence in the Black Sea basin and significant volcanic activity in the Anatolian region.<ref>{{cite journal |doi=10.1016/S0037-0738(02)00286-5|bibcode=2003SedG..156..149N |title=The Black Sea basin: tectonic history and Neogene–Quaternary rapid subsidence modelling |year=2003 |last1=Nikishin |first1=A. |journal=Sedimentary Geology |volume=156 |issue=1–4 |pages=149–168}}</ref> These geological mechanisms, in the long term, have caused the periodic isolations of the Black Sea from the rest of the global ocean system.

The large [[continental shelf|shelf]] to the north of the basin is up to {{convert|190|km|abbr=on}} wide and features a shallow apron with gradients between 1:40 and 1:1000. The southern edge around Turkey and the eastern edge around [[Georgia (country)|Georgia]], however, are typified by a narrow shelf that rarely exceeds {{convert|20|km|abbr=on}} in width and a steep apron that is typically 1:40 gradient with numerous submarine canyons and channel extensions. The [[Euxine abyssal plain]] in the center of the Black Sea reaches a maximum depth of {{convert|2212|m|2|abbr=off}} just south of [[Yalta]] on the [[Crimea|Crimean Peninsula]].<ref>{{cite book |title=Remote Sensing of the European Seas |year=2008 |isbn=978-1-4020-6771-6 |url=https://books.google.com/books?id=9B3D5-HBTzkC&pg=PA17 |page=17 |last1=Barale |first1=Vittorio |last2=Gade |first2=Martin|publisher=Springer }}</ref>

=== Chronostratigraphy ===
The Paleo-[[Euxinia]]n is described by the accumulation of [[Aeolian processes|eolian silt]] deposits (related to the [[Riss glaciation]]) and the lowering of sea levels ([[marine isotope stages|MIS]] 6, 8 and 10). The Karangat [[marine transgression]] occurred during the [[Eemian]] [[Interglacial]] (MIS 5e). This may have been the highest sea levels reached in the late [[Pleistocene]]. Based on this some scholars have suggested that the [[Crimean Peninsula]] was isolated from the mainland by a shallow strait during the Eemian Interglacial.<ref>{{cite book| url = https://books.google.com/books?id=PbEu2v0y7DYC| title = ''Geology and Geoarchaeology of the Black Sea Region: Beyond the Flood Hypothesis''| date = January 2011| publisher = Geological Society of America| isbn = 978-0-8137-2473-7}}</ref>

The Neoeuxinian transgression began with an inflow of waters from the [[Caspian Sea]]. Neoeuxinian deposits are found in the Black Sea below {{Convert|-20|m||abbr=on}} water depth in three layers. The upper layers correspond with the peak of the Khvalinian transgression, on the shelf shallow-water sands and [[coquina]] mixed with silty sands and brackish-water fauna, and inside the Black Sea Depression [[hydrotroilite]] silts. The middle layers on the shelf are sands with brackish-water mollusc shells. Of continental origin, the lower level on the shelf is mostly [[alluvial]] sands with pebbles, mixed with less common [[lacustrine]] silts and freshwater [[mollusc shell]]s. Inside the Black Sea Depression they are [[terrigenous sediment|terrigenous]] non-carbonate [[silt]]s, and at the foot of the [[continental slope]] [[turbidite]] sediments.<ref>{{cite journal |last1=Svitoch |first1=Alexander A. |title=The Neueuxinian basin of the Black Sea and Khvalinian transgression |journal=Quaternary International |date=2010 |volume=225 |pages=230–234 |doi=10.1016/j.quaint.2009.03.005}}</ref>

== Hydrology ==
[[File:The Danube Spills into the Black Sea.jpg|thumb|upright=1.35|This [[SeaWiFS]] view reveals the colorful interplay of currents on the sea's surface.]]

The Black Sea is the world's largest body of water with a [[meromictic]] basin.<ref name="Merriam">{{cite encyclopedia |url=http://www.merriam-webster.com/dictionary/meromictic |title=Meromictic |dictionary=Merriam-Webster |access-date=14 January 2014}}</ref> The deep waters do not mix with the upper layers of water that receive oxygen from the atmosphere. As a result, over 90% of the deeper Black Sea volume is [[Anoxic waters|anoxic]] water.<ref name="Exploring">{{cite web |url=http://www.ceoe.udel.edu/blacksea/research/index.html |title=Exploring Ancient Mysteries: A Black Sea Journey |publisher=University of Delaware |access-date=14 January 2014 |archive-date=16 June 2013 |archive-url=https://web.archive.org/web/20130616115917/http://www.ceoe.udel.edu/blacksea/research/index.html }}</ref> The Black Sea's circulation patterns are primarily controlled by basin topography and [[fluvial]] inputs, which result in a strongly stratified vertical structure. Because of the extreme stratification, it is classified as a [[estuary#Salt wedge|salt wedge estuary]].

Inflow from the [[Mediterranean Sea]] through the [[Dardanelles]] and [[Bosporus]] has a higher salinity and density than the outflow, creating the classic estuarine circulation. This means that the inflow of dense water from the Mediterranean occurs at the bottom of the basin while the outflow of fresher Black Sea surface-water into the [[Sea of Marmara]] occurs near the surface. The outflow is {{Convert|16000|m3/s||abbr=off}} or around {{Convert|500|km3/yr|cumi/yr|abbr=off}}, and the inflow is {{Convert|11000|m3/s||abbr=on}} or around {{Convert|350|km3/yr|cumi/yr|abbr=on}}.<ref name=Gregg>Gregg, M. C., and E. Özsoy (2002), "Flow, water mass changes, and hydraulics in the Bosporus", ''Journal of Geophysical Research'' 107(C3), 3016, {{doi|10.1029/2000JC000485}}</ref>

The following water budget can be estimated:{{when|reason=A date should be fixed as rates change significantly over time.|date=March 2022}}
* Water in: {{Convert|900|km3/year|cumi/year|abbr=on}}
** Total river discharge: {{Convert|370|km3/year|cumi/year|-1|abbr=on}}<ref>{{cite news |title=Black Sea Commission, State of Environment Report 2001–2006/7, Chap. 1B |url=http://www.blacksea-commission.org/_publ-SOE2009-CH1B.asp |access-date=29 January 2020 |archive-date=29 January 2020 |archive-url=https://web.archive.org/web/20200129185025/http://www.blacksea-commission.org/_publ-SOE2009-CH1B.asp }}</ref>
** Precipitation: {{Convert|180|km3/year|cumi/year|-1|abbr=on}}<ref name="Black_Sea_Commission">{{cite news |title=Black Sea Commission, State of Environment Report 2001–2006/7, Chap. 1A |url=http://www.blacksea-commission.org/_publ-SOE2009-CH1A.asp |access-date=29 January 2020 |archive-date=29 January 2020 |archive-url=https://web.archive.org/web/20200129202054/http://www.blacksea-commission.org/_publ-SOE2009-CH1A.asp }}</ref>
** Inflow via Bosporus: {{Convert|350|km3/year|cumi/year|-1|abbr=on}}<ref name="Gregg" />
* Water out: {{Convert|900|km3/year|cumi/year|-1|abbr=on}}
** Evaporation: {{Convert|400|km3/year|cumi/year|-1|abbr=on}} (reduced greatly since the 1970s)<ref name="Black_Sea_Commission" />
** Outflow via Bosporus: {{Convert|500|km3/year|cumi/year|-1|abbr=on}}<ref name="Gregg" />

The southern sill of the Bosporus is located at {{Convert|36.5|m||abbr=on}} below present sea level (deepest spot of the shallowest cross-section in the Bosporus, located in front of [[Dolmabahçe Palace]]) and has a wet section of around {{Convert|38000|m2||abbr=on}}.<ref name=Gregg /> Inflow and outflow current speeds are averaged around {{Convert|0.3 to 0.4|m/s||1|abbr=on}}, but much higher speeds are found locally, inducing significant turbulence and vertical shear. This allows for turbulent mixing of the two layers.<ref name=Talley>''Descriptive Physical Oceanography''. Talley, Pickard, Emery, Swift.</ref> Surface water leaves the Black Sea with a salinity of 17 [[Salinity#Seawater|practical salinity units]] (PSU) and reaches the Mediterranean with a salinity of 34 PSU. Likewise, an inflow of the Mediterranean with salinity 38.5 PSU experiences a decrease to about 34 PSU.<ref name=Talley />

Mean surface circulation is [[Cyclonic rotation|cyclonic]]; waters around the perimeter of the Black Sea circulate in a basin-wide shelfbreak [[gyre]] known as the Rim Current. The Rim Current has a maximum velocity of about {{Convert|50–100|cm/s||abbr=on}}. Within this feature, two smaller cyclonic gyres operate, occupying the eastern and western sectors of the basin.<ref name=Talley /> The Eastern and Western Gyres are well-organized systems in the winter but dissipate into a series of interconnected [[eddy (fluid dynamics)|eddies]] in the summer and autumn. Mesoscale activity in the peripheral flow becomes more pronounced during these warmer seasons and is subject to interannual variability.

Outside of the Rim Current, numerous quasi-permanent coastal eddies are formed as a result of [[upwelling]] around the coastal apron and "wind curl" mechanisms. The intra-annual strength of these features is controlled by seasonal atmospheric and fluvial variations. During the spring, the Batumi eddy forms in the southeastern corner of the sea.<ref name="Korotaev">{{Cite journal
| last1 = Korotaev | first1 = G.
| title = Seasonal, interannual, and mesoscale variability of the Black Sea upper layer circulation derived from altimeter data
| doi = 10.1029/2002JC001508
| journal = Journal of Geophysical Research
| volume = 108
| issue = C4
| page = 3122
| year = 2003
| article-number = 2002JC001508
| bibcode = 2003JGRC..108.3122K }}</ref>

Beneath the surface waters—from about {{Convert|50|to|100|m||abbr=}}—there exists a [[halocline]] that stops at the Cold Intermediate Layer (CIL). This layer is composed of cool, salty surface waters, which are the result of localized atmospheric cooling and decreased fluvial input during the winter months. It is the remnant of the winter surface mixed layer.<ref name=Talley /> The base of the CIL is marked by a major [[pycnocline]] at about {{convert|100|-|200|m|ft}}, and this density disparity is the major mechanism for isolation of the deep water.
[[File:OrduCoast.jpg|thumb|Black Sea coast in [[Ordu]], Turkey]]

Below the pycnocline is the Deep Water mass, where salinity increases to 22.3 PSU and temperatures rise to around {{Convert|8.9|C||abbr=}}.<ref name=Talley /> The hydrochemical environment shifts from oxygenated to anoxic, as bacterial decomposition of sunken biomass utilizes all of the free oxygen. Weak [[geothermal heating]] and long [[residence time]] create a very thick convective bottom layer.<ref name=Korotaev />

The [[Black Sea undersea river]] is a current of particularly saline water flowing through the Bosporus Strait and along the [[seabed]] of the Black Sea. The discovery of the river, announced on 1 August 2010, was made by scientists at the [[University of Leeds]] and is the first of its kind to be identified.<ref name="Gray">{{cite news |url=https://www.telegraph.co.uk/earth/environment/7920006/Undersea-river-discovered-flowing-on-sea-bed.html |archive-url=https://web.archive.org/web/20100802165402/http://www.telegraph.co.uk/earth/environment/7920006/Undersea-river-discovered-flowing-on-sea-bed.html |archive-date=2 August 2010 |title=Undersea river discovered flowing on sea bed |last=Gray |first=Richard |date=1 August 2010 |work=[[The Daily Telegraph]] |access-date=2 August 2010}}</ref> The undersea river stems from salty water spilling through the Bosporus Strait from the Mediterranean Sea into the Black Sea, where the water has a lower salt content.<ref name="Gray" />

== Hydrochemistry ==
Because of the anoxic water at depth, organic matter, including [[human impact on the environment|anthropogenic]] artifacts such as boat hulls, are well preserved. During periods of high surface productivity, short-lived [[algal bloom]]s form organic rich layers known as [[sapropel]]s. Scientists have reported an annual [[phytoplankton]] bloom that can be seen in many NASA images of the region.<ref>[http://earthobservatory.nasa.gov/NaturalHazards/natural_hazards_v2.php3?img_id=3669 Black Sea Becomes Turquoise] {{webarchive|url=https://web.archive.org/web/20081028221745/http://earthobservatory.nasa.gov/NaturalHazards/natural_hazards_v2.php3?img_id=3669 |date=28 October 2008 }} earthobservatory.nasa.gov. Retrieved 2 December 2006.</ref> As a result of these characteristics the Black Sea has gained interest from the field of [[marine archaeology]], as ancient shipwrecks in excellent states of preservation have been discovered, such as the [[Byzantine]] wreck [[Sinop D]], located in the anoxic layer off the coast of [[Sinop, Turkey]].

Modelling shows that, in the event of an [[asteroid impact]] on the Black Sea, the release of [[hydrogen sulfide]] clouds would pose a threat to health—and perhaps even life—for people living on the Black Sea coast.<ref>{{cite journal |doi=10.1007/s11069-006-0017-7 |title=Asteroid impact in the Black Sea. Death by drowning or asphyxiation? |year=2006 |last1=Schuiling |first1=Roelof Dirk |last2=Cathcart |first2=Richard B. |last3=Badescu |first3=Viorel |last4=Isvoranu |first4=Dragos |last5=Pelinovsky |first5=Efim |journal=Natural Hazards |volume=40 |issue=2 |pages=327–338 |s2cid=129038790}}</ref>

There have been isolated reports of flares on the Black Sea occurring during thunderstorms, possibly caused by lightning igniting combustible gas seeping up from the sea depths.<ref>{{cite web |url=http://www.cosis.net/abstracts/EGU2007/01654/EGU2007-J-01654.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://www.cosis.net/abstracts/EGU2007/01654/EGU2007-J-01654.pdf |archive-date=9 October 2022 |url-status=live |title=Asteroid impact in the Black Sea: tsunami and toxic gas emission |website=www.cosis.net}}</ref>

== Ecology ==
=== Marine ===
{{See also|List of fish of the Black Sea}}
[[File:POTI.JPG|right|thumb|The port of [[Poti]], Georgia]]

The Black Sea supports an active and dynamic marine ecosystem, dominated by species suited to the [[brackish]], nutrient-rich, conditions. As with all marine food webs, the Black Sea features a range of [[Trophic level|trophic]] groups, with [[autotroph]]ic algae, including [[diatom]]s and [[dinoflagellate]]s, acting as primary producers. The fluvial systems draining Eurasia and central Europe introduce large volumes of sediment and dissolved nutrients into the Black Sea, but the distribution of these nutrients is controlled by the degree of physiochemical stratification, which is, in turn, dictated by seasonal physiographic development.<ref name="Oguz99">{{cite journal |author=Oguz, T. |author2=H. W. Ducklow |year=1999 |title=A physical-biochemical model of plankton productivity and nitrogen cycling in the Black Sea |url=http://www.ims.metu.edu.tr/cv/oguz/PDFs/oguz_etal_DSR99.pdf |journal=Deep-Sea Research Part I |volume=46 |issue=4 |pages=597–636 |doi=10.1016/S0967-0637(98)00074-0 |bibcode=1999DSRI...46..597O |display-authors=etal |hdl=11511/68400 |archive-url=https://web.archive.org/web/20120426061730/http://www.ims.metu.edu.tr/cv/Oguz/PDFs/oguz_etal_DSR99.pdf |archive-date=26 April 2012}}</ref>

During winter, strong winds promote convective overturning and upwelling of nutrients, while high summer temperatures result in marked vertical stratification and a warm, shallow mixed layer.<ref name="Oguz">{{cite journal |author1=Oguz, T. |author2=A. Merico |name-list-style=amp |year=2006 |title=Factors controlling the summer Emiliania huxleyi bloom in the Black Sea: A modeling study |journal=Journal of Marine Systems |volume=59 |issue=3–4 |pages=173–188 |url=http://www.ims.metu.edu.tr/cv/oguz/PDFs/JMS_EHUX_article.pdf |doi=10.1016/j.jmarsys.2005.08.002 |bibcode=2006JMS....59..173O |hdl=11511/65313 |archive-url=https://web.archive.org/web/20120426061804/http://www.ims.metu.edu.tr/cv/oguz/PDFs/JMS_EHUX_article.pdf |archive-date=26 April 2012}}</ref> Day length and [[insolation]] intensity also control the extent of the [[photic zone]]. Subsurface productivity is limited by nutrient availability, as the anoxic bottom waters act as a sink for reduced [[nitrate]], in the form of [[ammonia]]. The [[benthic zone]] also plays an important role in Black Sea nutrient cycling, as chemosynthetic organisms and anoxic geochemical pathways recycle nutrients which can be upwelled to the photic zone, enhancing productivity.<ref>{{cite journal |author=Friedrich, J. |author2=C. Dinkel |year=2002 |title=Benthic Nutrient Cycling and Diagenetic Pathways in the North-western Black Sea |doi=10.1006/ecss.2000.0653 |url=http://epic.awi.de/Publications/Fri2002d.pdf |journal=[[Estuarine, Coastal and Shelf Science]] |volume=54 |issue=3 |pages=369–383 |bibcode=2002ECSS...54..369F |display-authors=etal |archive-url=https://web.archive.org/web/20111004001522/http://epic.awi.de/Publications/Fri2002d.pdf |archive-date=4 October 2011 }}</ref>

In total, the Black Sea's biodiversity contains around one-third of the Mediterranean's and is experiencing natural and artificial invasions or "Mediterranizations".<ref>[http://www.blackmeditjournal.org/pdf/Vol%2017%20(3)%20%20pdf%205.pdf Mechanisms impeding the natural Mediterranization process of Black Sea fauna] {{Webarchive|url=https://web.archive.org/web/20170812054605/http://www.blackmeditjournal.org/pdf/Vol%2017%20(3)%20%20pdf%205.pdf |date=12 August 2017 }} (pdf). Retrieved on 6 September 2017</ref><ref>Selifonova, P.J. (2011). [http://www.acta-zoologica-bulgarica.eu/downloads/acta-zoologica-bulgarica/2011/63-1-077-084.pdf Ships' ballast as a Primary Factor for 'Mediterranization' of Pelagic Copepod Fauna (Copepoda) in the Northeastern Black Sea] {{Webarchive|url=https://web.archive.org/web/20171020090426/http://www.acta-zoologica-bulgarica.eu/downloads/acta-zoologica-bulgarica/2011/63-1-077-084.pdf |date=20 October 2017 }} (pdf). Retrieved on 6 September 2017</ref>

==== Phytoplankton ====
[[File:Black Sea Nasa May 25 2004.jpg|thumb|upright=1.35|[[Phytoplankton]] blooms and plumes of sediment form the bright blue swirls that ring the Black Sea in this 2004 image.]]

The main phytoplankton groups present in the Black Sea are [[dinoflagellate]]s, [[diatom]]s, [[coccolithophore]]s and [[cyanobacteria]]. Generally, the annual cycle of phytoplankton development comprises significant diatom and dinoflagellate-dominated spring production, followed by a weaker mixed assemblage of community development below the seasonal thermocline during summer months, and surface-intensified autumn production.<ref name="Oguz" /><ref>{{cite journal |author=Eker, E. |author2=L. Georgieva |year=1999 |title=Phytoplankton distribution in the western and eastern Black Sea in spring and autumn 1995 |journal=ICES Journal of Marine Science |volume=56 |pages=15–22 |url=http://www.ims.metu.edu.tr/cv/kideys/EkerICES.pdf |doi=10.1006/jmsc.1999.0604 |bibcode=1999ICJMS..56...15E |hdl=11511/32054 |display-authors=etal |archive-url=https://web.archive.org/web/20120426061841/http://www.ims.metu.edu.tr/cv/kideys/EkerICES.pdf |archive-date=26 April 2012 |hdl-access=free}}</ref> This pattern of productivity is augmented by an ''[[Emiliania huxleyi]]'' bloom during the late spring and summer months.
* [[Dinoflagellate]]s
: Annual dinoflagellate distribution is defined by an extended bloom period in subsurface waters during the late spring and summer. In November, subsurface plankton production is combined with surface production, due to vertical mixing of water masses and nutrients such as [[nitrite]].<ref name="Oguz99" /> The major bloom-forming dinoflagellate species in the Black Sea is ''[[Gymnodinium]]'' sp.<ref name="Eker-Develi, E 2003">{{cite journal |doi=10.1016/S0924-7963(03)00031-9 |bibcode=2003JMS....39..203E |title=Distribution of phytoplankton in the southern Black Sea in summer 1996, spring and autumn 1998 |year=2003 |last1=Eker-Develi |first1=E. |journal=Journal of Marine Systems |volume=39 |issue=3–4 |pages=203–211|hdl=11511/31414 |hdl-access=free }}</ref> Estimates of dinoflagellate diversity in the Black Sea range from 193<ref>Krakhmalny, A. F. (1994). "Dinophyta of the Black Sea (Brief history of investigations and species diversity)." ''Algologiya'' 4: 99–107.</ref> to 267 species.<ref name="Gomez">{{cite journal |author1=Gomez, F. |author2=L. Briceno |name-list-style=amp |year=2004 |title=An annotated checklist of dinoflagellates in the Black Sea |journal= [[Hydrobiologia]] |volume=517 |issue=1 |pages=43–59 |url=http://www.environmental-expert.com/Files%5C24723%5Carticles%5C15660%5C2.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://www.environmental-expert.com/Files%5C24723%5Carticles%5C15660%5C2.pdf |archive-date=9 October 2022 |url-status=live |doi=10.1023/B:HYDR.0000027336.05452.07 |bibcode=2004HyBio.517...43G |s2cid=30559038 }}</ref> This level of species richness is relatively low in comparison to the Mediterranean Sea, which is attributable to the brackish conditions, low water transparency and presence of [[Anoxic waters|anoxic]] bottom waters. It is also possible that the low winter temperatures below {{convert|4|°C}} of the Black Sea prevent [[thermophilous]] species from becoming established. The relatively high organic matter content of Black Sea surface water favors the development of [[heterotroph]]ic (an organism that uses organic carbon for growth) and mixotrophic dinoflagellates species (able to exploit different trophic pathways), relative to autotrophs. Despite its unique hydrographic setting, there are no confirmed [[endemism|endemic]] dinoflagellate species in the Black Sea.<ref name="Gomez" />
* [[Diatom]]s
: The Black Sea is populated by many species of the marine diatom, which commonly exist as colonies of [[unicellular]], non-motile auto- and heterotrophic [[algae]]. The life-cycle of most diatoms can be described as 'boom and bust' and the Black Sea is no exception, with diatom blooms occurring in surface waters throughout the year, most reliably during March.<ref name="Oguz99" /> In simple terms, the phase of rapid population growth in diatoms is caused by the in-wash of [[silicon]]-bearing terrestrial sediments, and when the supply of silicon is exhausted, the diatoms begin to sink out of the photic zone and produce resting [[cyst]]s. Additional factors such as predation by zooplankton and [[ammonium]]-based regenerated production also have a role to play in the annual diatom cycle.<ref name="Oguz99" /><ref name="Oguz" /> Typically, {{lang|la|Proboscia alata}} blooms during spring and {{lang|la|Pseudosolenia calcar-avis}} blooms during the autumn.<ref name="Eker-Develi, E 2003" />
* [[Coccolithophore]]s
: Coccolithophores are a type of [[Motility|motile]], [[autotrophic]] [[phytoplankton]] that produce CaCO<sub>3</sub> plates, known as [[coccolith]]s, as part of their life cycle. In the Black Sea, the main period of coccolithophore growth occurs after the bulk of the dinoflagellate growth has taken place. In May, the dinoflagellates move below the seasonal [[thermocline]] into deeper waters, where more nutrients are available. This permits coccolithophores to utilize the nutrients in the upper waters, and by the end of May, with favorable light and temperature conditions, growth rates reach their highest. The major bloom-forming species is {{lang|la|[[Emiliania huxleyi]]}}, which is also responsible for the release of [[dimethyl sulfide]] into the atmosphere. Overall, coccolithophore diversity is low in the Black Sea, and although recent sediments are dominated by {{lang|la|E. huxleyi}} and {{lang|la|Braarudosphaera bigelowii}}, [[Holocene]] sediments have been shown to also contain Helicopondosphaera and Discolithina species.
* [[Cyanobacteria]]
: Cyanobacteria are a phylum of [[picoplankton]]ic (plankton ranging in size from 0.2 to 2.0 [[micrometre|μm]]) [[bacteria]] that obtain their energy via [[photosynthesis]], and are present throughout the world's oceans. They exhibit a range of morphologies, including filamentous colonies and [[biofilm]]s. In the Black Sea, several species are present, and as an example, ''Synechococcus'' spp. can be found throughout the photic zone, although concentration decreases with increasing depth. Other factors which exert an influence on distribution include nutrient availability, predation, and salinity.<ref>{{cite journal |title=Vertical distribution of marine cyanobacteria Synechococcus spp. in the Black, Marmara, Aegean, and eastern Mediterranean seas |doi=10.1016/j.dsr2.2006.03.016 |year=2006 |last1=Uysal |first1=Z. |journal=Deep-Sea Research Part II |volume=53 |issue=17–19 |pages=1976–1987 |bibcode=2006DSRII..53.1976U|hdl=11511/32538 |hdl-access=free }}</ref>

==== Animal species ====
* [[Zebra mussel]]
: The Black Sea along with the [[Caspian Sea]] is part of the zebra mussel's native range. The mussel has been accidentally introduced around the world and become an [[invasive species]] where it has been introduced.
* [[Common carp]]
: The common carp's native range extends to the Black Sea along with the Caspian Sea and [[Aral Sea]]. Like the zebra mussel, the common carp is an invasive species when introduced to other habitats.
* [[Round goby]]
: Another native fish that is also found in the Caspian Sea. It preys upon zebra mussels. Like the mussels and common carp, it has become invasive when introduced to other environments, like the [[Great Lakes]] in North America.
* [[File:Dolphins swim near ferry in port of Batumi 150505-A-PU919-7446.jpg|thumb|right|upright=1.2|Common dolphins [[cetacean surfacing behaviour|porpoising]] with a ferry at [[Batumi]] port]]Marine mammals and marine [[megafauna]]
: Marine mammals present within the basin include subspecies of two species of dolphin ([[common dolphin|common]]<ref>{{cite iucn |author=Birkun Jr. |author2=A.A. |year=2008 |title=''Delphinus delphis'' ssp. ''ponticus'' |volume=2008 |article-number=e.T133729A3875256 |doi=10.2305/IUCN.UK.2008.RLTS.T133729A3875256.en |access-date=22 November 2025}}</ref> and [[Black Sea bottlenose dolphin|bottlenose]]<ref>{{cite iucn |author=Birkun, A. |year=2012 |title=''Tursiops truncatus'' ssp. ''ponticus'' |volume=2012 |article-number=e.T133714A17771698 |doi=10.2305/IUCN.UK.2012.RLTS.T133714A17771698.en |access-date=22 November 2025}}</ref>) and the [[harbour porpoise]],<ref>{{cite iucn |author=Birkun Jr. |author2=A.A. |author3=Frantzis, A. |year=2008 |title=''Phocoena phocoena'' ssp. ''relicta'' |volume=2008 |article-number=e.T17030A6737111 |doi=10.2305/IUCN.UK.2008.RLTS.T17030A6737111.en |access-date=22 November 2025}}</ref> although all of these are endangered due to pressures and impacts by human activities. All three species have been classified as distinct subspecies from those in the Mediterranean and the Atlantic and are endemic to the Black and [[Sea of Azov|Azov]] seas, and are more active during nights in the Turkish Straits.<ref name="Risso's">[http://www.blackmeditjournal.org/pdf/121_126.pdf First stranding record of a Risso's Dolphin (Grampus griseus) in the Marmara Sea, Turkey] {{Webarchive|url=https://web.archive.org/web/20171020090832/http://www.blackmeditjournal.org/pdf/121_126.pdf |date=20 October 2017 }} (pdf). Retrieved on 6 September 2017</ref> However, construction of the [[Crimean Bridge]] has caused increases in nutrients and planktons in the waters, attracting large numbers of fish and more than 1,000 bottlenose dolphins.<ref>Goldman E.. 2017. [http://rbth.com/politics_and_society/2017/02/28/crimean-bridge-construction-boosts-dolphin-population-in-kerch-strait_711003 Crimean bridge construction boosts dolphin population in Kerch Strait] {{Webarchive|url=https://web.archive.org/web/20170228190132/http://rbth.com/politics_and_society/2017/02/28/crimean-bridge-construction-boosts-dolphin-population-in-kerch-strait_711003 |date=28 February 2017 }}. ''[[Russia Beyond the Headlines]]''. Retrieved on 10 March 2017.</ref> However, others claim that construction may cause devastating damages to the ecosystem, including dolphins.<ref>Reznikova E.. 2017. [https://primechaniya.ru/home/news/fevral-2017/krymskie_strojki_ubivayut_vse_zhivoe_na_dne_morya/ Крымские стройки убивают все живое на дне моря] {{Webarchive|url=https://web.archive.org/web/20170929183831/https://primechaniya.ru/home/news/fevral-2017/krymskie_strojki_ubivayut_vse_zhivoe_na_dne_morya/ |date=29 September 2017 }}. Примечания. Новости Севастополя и Крыма. Retrieved on 29 September 2017</ref>
: [[Mediterranean monk seal]]s, now a vulnerable species, were historically abundant in the Black Sea, and are regarded to have become extinct from the basin in 1997.<ref name="iucn">{{cite iucn |author=Karamanlidis, A.A. |author2=Dendrinos, P. |author3=Kıraç, C.O. |author4=Nicolaou, H. |author5=Pires, R. |year=2023 |title=''Monachus monachus'' (Europe assessment) |volume=2023 |article-number=e.T13653A216670068 |doi= |access-date=28 April 2025}}</ref> Monk seals were present at [[Snake Island (Black Sea)|Snake Island]], near the [[Danube Delta]], until the 1950s, and several locations such as the {{interlanguage link|Danube Plavni Nature Reserve|ru|Дунайский биосферный заповедник}} and [[Doğankent]] were the last of the seals' [[hauling-out]] sites post-1990.<ref name="BlackPedia">{{Cite book | url=https://books.google.com/books?id=KFCqBAAAQBAJ&q=azov+sea+monk+seal&pg=PA532 | title=The Black Sea Encyclopedia| isbn=978-3-642-55227-4| last1=Grinevetsky| first1=Sergei R.| last2=Zonn| first2=Igor S.| last3=Zhiltsov| first3=Sergei S.| last4=Kosarev| first4=Aleksey N.| last5=Kostianoy| first5=Andrey G.| date=30 September 2014| publisher=Springer}}</ref> Very few animals still thrive in the [[Sea of Marmara]].<ref>{{cite journal |doi=10.1080/09397140.2014.944438 | volume=60 | issue=3 | title=A new sighting of the Mediterranean Monk Seal, Monachus monachus (Hermann, 1779), in the Marmara Sea (Turkey) | journal=Zoology in the Middle East | pages=278–280| year=2014 | last1=Emek Inanmaz | first1=Özgür | last2=Değirmenci | first2=Özgür | last3=Gücü | first3=Ali Cemal | s2cid=83515152 | hdl=11511/30671 | hdl-access=free }}</ref>
: Ongoing Mediterranizations may or may not boost cetacean diversity in the Turkish Straits<ref name="Risso's" /> and hence in the Black and Azov basins.
: Various species of [[pinniped]]s, [[sea otter]], and [[beluga whale]]<ref name="GreekCetacea">{{cite journal |author=Frantzis A. |author2=Alexiadou P. |author3=Paximadis G. |author4=Politi E. |author5=Gannier A. |author6=Corsini-Foka M. |year=2023 |title=Current knowledge of the cetacean fauna of the Greek Seas |url=http://cetaceanalliance.org/download/literature/Frantzis_etal_2003.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://cetaceanalliance.org/download/literature/Frantzis_etal_2003.pdf |archive-date=9 October 2022 |url-status=live |journal=Journal of Cetacean Research and Management |volume=5 |issue=3 |pages=219–232 |doi=10.47536/jcrm.v5i3.801 |s2cid=56221055 |access-date=21 April 2016}}</ref><ref>Anderson R. (1992). [https://www.chicagotribune.com/1992/03/12/black-sea-whale-aided-by-activists/ Black Sea Whale Aided By Activists]. ''[[Chicago Tribune]]''. Retrieved on 21 April 2016</ref> were introduced into the Black Sea by mankind and later escaped either by accidental or purported causes. Of these, [[grey seal]]s<ref>{{cite journal |url=https://www.researchgate.net/publication/235948607 |title=Grey seal Halichoerus grypus in the Black Sea: The first case of long-term survival of an exotic pinniped |first1=E.V. |last1=Gladilina |first2=Oleg |last2=Kovtun |first3=Andrey |last3=Kondakov |first4=A.M. |last4=Syomik |first5=K.K. |last5=Pronin |first6=Pavel |last6=Gol'din |date=1 January 2013 |journal=Marine Biodiversity Records |volume=6 |article-number=e33 |via=ResearchGate |doi=10.1017/S1755267213000018|bibcode=2013MBdR....6E..33G }}</ref> and beluga whales<ref name="GreekCetacea" /> have been recorded with successful, long-term occurrences.
: [[Great white shark]]s are known to reach into the Sea of Marmara and Bosporus Strait and [[basking shark]]s into the Dardanelles, although it is unclear whether or not these sharks may reach into the Black and Azov basins.<ref>{{Cite journal |url=http://elasmollet.org/PublicationsOthers/Kabasakal2014_WS_Turkey.pdf |archive-url=https://web.archive.org/web/20150616052627/http://elasmollet.org/PublicationsOthers/Kabasakal2014_WS_Turkey.pdf |archive-date=16 June 2015 |url-status=usurped |doi=10.1017/S1755267214000980|title=The status of the great white shark (Carcharodon carcharias) in Turkey's waters |journal=Marine Biodiversity Records |volume=7 |year=2014 |last1=Kabasakal |first1=Hakan|article-number=e109 |bibcode=2014MBdR....7E.109K }}</ref><ref>Cuma (2009). [http://www.arenagazetesi.com.tr/haber/Canakkale-de-10-metrelik-kopekbaligi/58982 Çanakkale'de 10 metrelik köpekbalığı!] {{Webarchive|url=https://web.archive.org/web/20170904154004/http://www.arenagazetesi.com.tr/haber/Canakkale-de-10-metrelik-kopekbaligi/58982 |date=4 September 2017 }}. Retrieved on 4 September 2017</ref>

==== Ecological effects of pollution ====
Since the 1960s, rapid industrial expansion along the Black Sea coastline and the construction of a major dam on the Danube have significantly increased annual variability in the N:P:Si ratio in the basin. Coastal areas, accordingly, have seen an increase in the frequency of monospecific phytoplankton blooms, with diatom-bloom frequency increasing by a factor of 2.5 and non-diatom bloom frequency increasing by a factor of 6. The non-diatoms, such as the prymnesiophytes {{lang|la|Emiliania huxleyi}} (coccolithophore), {{lang|la|Chromulina}} sp., and the Euglenophyte {{lang|la|Eutreptia lanowii}}, can out-compete diatom species because of the limited availability of silicon, a necessary constituent of diatom frustules.<ref>{{cite journal |title =Effect of Danube River dam on Black Sea biogeochemistry and ecosystem structure |doi =10.1038/386385a0 |year =1997 |last1 =Humborg |first1 =Christoph |last2 =Ittekkot |first2 =Venugopalan |last3 =Cociasu |first3 =Adriana |last4 =Bodungen |first4 =Bodo v. |journal =Nature |volume =386 |issue =6623 |pages =385–388 |bibcode=1997Natur.386..385H |s2cid=4347576}}</ref> As a consequence of these blooms, benthic macrophyte populations were deprived of light, while anoxia caused mass mortality in marine animals.<ref>{{cite book |author =Sburlea, A. |author2=L. Boicenco |title=Chemicals as Intentional and Accidental Global Environmental Threats |chapter =Aspects of Eutrophication as a Chemical Pollution with Implications on Marine Biota at the Romanian Black Sea Shore |year =2006 |doi =10.1007/978-1-4020-5098-5_28 |pages =357–360 |series =NATO Security through Science Series |isbn =978-1-4020-5096-1 |display-authors =etal}}</ref><ref>{{cite journal |author =Gregoire, M. |author2 =C. Raick |title =Numerical modeling of the central Black Sea ecosystem functioning during the eutrophication phase |doi =10.1016/j.pocean.2008.01.002 |year =2008 |journal =Progress in Oceanography |volume =76 |issue =3 |pages=286–333 |bibcode =2008PrOce..76..286G |display-authors=etal}}</ref>

Overfishing during the 1970s further compounded the decline in macrophytes, while the invasive ctenophore ''Mnemiopsis'' reduced the biomass of [[copepod]]s and other zooplankton in the late 1980s. Additionally, an alien species—the [[warty comb jelly]] ({{lang|la|Mnemiopsis leidyi}})—established itself in the basin, exploding from a few individuals to an estimated biomass of one billion metric tons.<ref>{{cite book |author =Colin Woodard |title =Ocean's end: travels through endangered seas |url=https://books.google.com/books?id=QsVeUi_XbF4C&pg=PA1 |archive-url =https://web.archive.org/web/20130616130012/http://books.google.com/books?id=QsVeUi_XbF4C&pg=PA1 |archive-date =16 June 2013 |access-date =1 August 2011 |date =11 February 2001 |publisher =Basic Books |isbn =978-0-465-01571-9 |pages=1–28 }}</ref>

Pollution-reduction and regulation efforts led to a partial recovery of the Black Sea ecosystem during the 1990s, and an EU monitoring exercise, 'EROS21', revealed decreased nitrogen and phosphorus values relative to the 1989 peak.<ref>{{cite journal |doi=10.1006/ecss.2000.0659 |url=http://www.physoz.icbm.de/download/sebastian/ECSS_lsebs.pdf |archive-url =https://ghostarchive.org/archive/20221009/http://www.physoz.icbm.de/download/sebastian/ECSS_lsebs.pdf |archive-date =9 October 2022 |url-status =live |title =Modelling the Danube-influenced North-western Continental Shelf of the Black Sea. II: Ecosystem Response to Changes in Nutrient Delivery by the Danube River after its Damming in 1972 |year=2002 |last1 =Lancelot |first1=C. |journal=Estuarine, Coastal and Shelf Science |volume=54 |issue=3 |pages=473–499 |bibcode =2002ECSS...54..473L}}</ref> Recently,{{when|date=November 2024}} scientists have noted signs of ecological recovery, in part due to the construction of new [[sewage treatment|sewage-treatment]] plants in Slovakia, Hungary, Romania, and Bulgaria in connection with those countries' membership of the European Union. {{lang|la|Mnemiopsis leidyi}} populations have been checked with the arrival of another alien species that feeds on them.<ref>[http://www.colinwoodard.com/ Woodard, Colin] {{Webarchive|url =https://web.archive.org/web/20130512171719/http://www.colinwoodard.com/ |date=12 May 2013 }}, [http://www.cqpress.com/docs/AffiliationsPDFs/oceans.pdf "The Black Sea's Cautionary Tale"], {{Webarchive|url =https://web.archive.org/web/20090207134218/http://www.cqpress.com/docs/AffiliationsPDFs/oceans.pdf |date=7 February 2009 }} ''Congressional Quarterly Global Researcher'', October 2007, pp. 244–245</ref>{{Request quotation|date=July 2025}} However other sources say that there was ecological decline in the early 21st century.<ref>{{Cite web |title= Convention on the Protection of the Black Sea Against Pollution (Bucharest Convention) / Republic of Türkiye Ministry of Foreign Affairs|url=https://www.mfa.gov.tr/convention-on-the-protection-of-the-black-sea-against-pollution-_bucharest-convention_.en.mfa#:~:text=As%20being%20one%20of%20the,flow%20into%20the%20Black%20Sea.}}</ref>

<gallery mode="packed">
File:black sea fauna jelly 01.jpg|[[Jellyfish]]
File:black sea fauna actinia 01.jpg|[[Sea anemone|Actinia]]
File:black sea fauna actinia 02.JPG|Actinia
File:black sea fauna goby 01.jpg|[[Goby]]
File:black sea fauna stingray 01.jpg|[[Stingray]]
File:Black sea mullus barbatus ponticus 01.jpg|[[Mullus barbatus|Goat fish]]
File:Black sea fauna hermit crab 01.jpg|[[Hermit crab]], ''[[Diogenes pugilator]]''
File:Black sea fauna blue sponge.jpg|Blue [[sponge]]
File:Squalus acanthias2.jpg|[[Spiny dogfish]]
File:Black Sea fauna Seahorse.JPG|[[Seahorse]]
File:Kitesurfer and Dolphins Cropped.jpg|[[common dolphin|Black Sea common dolphins]] with a [[kiteboarding|kite-surfer]] off [[Sochi]]
</gallery>

== History ==
=== Mediterranean connection during the Holocene ===
[[File:Istanbul and Bosporus big.jpg|thumb|right|upright|The [[Bosporus]], taken from the [[International Space Station]]]]

The Black Sea is connected to the [[World Ocean]] by a chain of two shallow [[strait]]s, the [[Dardanelles]] and the [[Bosporus]]. The Dardanelles is {{convert|55|m|abbr=on}} deep, and the Bosporus is as shallow as {{convert|36|m|abbr=on}}. By comparison, at the height of the [[Last Glacial Period|last ice age]], sea levels were more than {{convert|100|m|abbr=on}} lower than they are now.
[[File:Dardanelles map2.png|thumb|upright=1.35|Map of the [[Dardanelles]]]]
There is evidence that water levels in the Black Sea were considerably lower at some point during the post-glacial period. Some researchers theorize that the Black Sea had been a landlocked freshwater lake (at least in upper layers) during the last glaciation and for some time after.

In the aftermath of the last glacial period, water levels in the Black Sea and the [[Aegean Sea]] rose independently until they were high enough to exchange water. The exact timeline of this development is still subject to debate. One possibility is that the Black Sea filled first, with excess freshwater flowing over the Bosporus sill and eventually into the Mediterranean Sea. There are also catastrophic scenarios, such as the "[[Black Sea deluge hypothesis]]" put forward by [[William Ryan (geologist)|William Ryan]], [[Walter C. Pitman III|Walter Pitman]] and [[Petko Dimitrov]].

==== Deluge hypothesis ====
{{Main|Black Sea deluge hypothesis}}
The '''Black Sea deluge''' is a hypothesized catastrophic rise in the level of the Black Sea {{c.|5600{{spaces}}BC}} due to waters from the [[Mediterranean Sea]] breaching a sill in the [[Bosporus]] Strait. The hypothesis was headlined when ''[[The New York Times]]'' published it in December 1996, shortly before it was published in an [[academic journal]].<ref>{{Cite news |first=John Noble |last=Wilford |title=Geologists Link Black Sea Deluge to Farming's Rise |work=[[The New York Times]] |date=17 December 1996 |access-date=17 June 2013 |url=https://www.nytimes.com/1996/12/17/science/geologists-link-black-sea-deluge-to-farming-s-rise.html}}</ref> While it is agreed that the sequence of events described did occur, there is debate over the suddenness, dating, and magnitude of the events. Relevant to the hypothesis is that its description has led some to connect this catastrophe with prehistoric [[flood myth]]s.<ref>{{cite book |author1=William Ryan |author2=Walter Pitman |name-list-style=amp |title=Noah's Flood: The New Scientific Discoveries About the Event That Changed History |publisher=[[Simon & Schuster]] Paperbacks |place=New York |year=1998 |isbn=0-684-85920-3 |url=https://archive.org/details/isbn_9780684859200 }}</ref><ref>Dimitrov P., D. Dimitrov. 2004. [https://www.researchgate.net/publication/290938137_The_Black_Sea_The_Flood_and_the_ancient_myths The Black Sea The Flood and the ancient myths] {{Webarchive|url=https://web.archive.org/web/20210515095644/https://www.researchgate.net/publication/290938137_The_Black_Sea_The_Flood_and_the_ancient_myths |date=15 May 2021 }}. "Slavena", Varna, ISBN 954-579-335-X, 91 p., DOI: 10.13140/RG.2.2.18954.16327</ref>

=== Archaeology ===
[[File:Aivazovsky - Black Sea Fleet in the Bay of Theodosia.jpg|thumb|upright=1.15|[[Ivan Aivazovsky]]. ''Black Sea Fleet in the Bay of Theodosia'', just before the [[Crimean War]]]]
The Black Sea was sailed by [[Hittites]], [[Carians]], [[Colchis|Colchians]], [[Armenians]], [[Thracians]], [[Ancient Greece|Greeks]], [[Achaemenid Empire|Persians]], [[Cimmerians]], [[Scythians]], [[Ancient Rome|Romans]], [[Byzantine Greeks|Byzantines]], [[Goths]], [[Huns]], [[Pannonian Avars|Avars]], [[Slavs]], [[Varangians]], [[Crusaders]], [[Republic of Venice|Venetians]], [[Republic of Genoa|Genoese]], [[Colchis|Georgians]], [[Bulgarians]], [[Tatars]] and [[Ottoman Empire|Ottomans]].

The concentration of [[historical powers]], combined with the preservative qualities of the deep [[anoxic waters]] of the Black Sea, has attracted increased interest from [[maritime archaeology|marine archaeologists]] who have begun to discover a large number of [[Ancient Black Sea shipwrecks|ancient ships and organic remains]] in a high state of preservation.

=== Recorded history ===
[[File:Diego-homem-black-sea-ancient-map-1559.jpg|thumb|upright=1.35|left|A 16th-century map of the Black Sea by [[Diogo Homem]]]]
The Black Sea was a busy waterway on the crossroads of the ancient world: the [[Balkans]] to the west, the Eurasian [[steppe]]s to the north, the [[Caucasus]] and [[Central Asia]] to the east, [[Asia Minor]] and [[Mesopotamia]] to the south, and [[Greece]] to the southwest.

The land at the eastern end of the Black Sea, [[Colchis]] (in present-day [[Georgia (country)|Georgia]]), marked for the [[Ancient Greece|ancient Greeks]] the edge of the known world.
[[File:Pontos Euxeinos.gif|thumb|upright=1.35|[[Colonies in antiquity|Greek colonies]] (8th–3rd century BC) of the Black Sea (Euxine, or "hospitable" sea)]]
The [[Pontic–Caspian steppe]] to the north of the Black Sea is seen by several researchers as the pre-historic [[Proto-Indo-European homeland|original homeland]] ({{lang | de | [[Urheimat]]}}) of the speakers of the [[Proto-Indo-European language]] (PIE).<ref>
{{cite book | url = https://books.google.com/books?id=nLIufwC4szwC | title= The Horse, the Wheel, and Language: How Bronze-Age Riders from the Eurasian Steppes Shaped the Modern World | author= David W. Anthony | isbn= 978-0-691-14818-2 | publisher= Princeton University Press | date= 2010 | quote = I believe with many others that the proto-Indo-European homeland was located in the steppes north of the Black and Caspian Seas in what is today southern Ukraine and Russia.}}
</ref><ref>
{{cite journal |url= https://www.biorxiv.org/content/early/2015/02/10/013433 | title= Massive migration from the steppe is a source for Indo-European languages in Europe | first1= Wolfgang | last1= Haak | first2= Iosif | last2= Lazaridis | first3= Nick | last3= Patterson | first4= Nadin | last4= Rohland | first5= Swapan | last5= Mallick | first6= Bastien | last6= Llamas | first7= Guido | last7= Brandt | first8= Susanne | last8= Nordenfelt | first9= Eadaoin | last9= Harney | first10= Kristin | last10= Stewardson | first11= Qiaomei | last11= Fu | first12= Alissa | last12= Mittnik | first13= Eszter | last13= Bánffy | first14= Christos | last14= Economou | first15= Michael | last15= Francken | first16= Susanne | last16= Friederich | first17= Rafael Garrido | last17= Pena | first18= Fredrik | last18= Hallgren | first19= Valery | last19= Khartanovich | first20= Aleksandr | last20= Khokhlov | first21= Michael | last21= Kunst | first22= Pavel | last22= Kuznetsov | first23= Harald | last23= Meller | first24= Oleg | last24= Mochalov | first25= Vayacheslav | last25= Moiseyev | first26= Nicole | last26= Nicklisch |first27= Sandra L. |last27= Pichler |first28= Roberto | last28= Risch | first29= Manuel A. Rojo | last29= Guerra | first30= Christina | last30= Roth | first31= Anna | last31= Szécsényi-Nagy | first32= Joachim | last32= Wahl | first33= Matthias | last33= Meyer | first34= Johannes | last34= Krause | first35= Dorcas | last35= Brown | first36= David | last36= Anthony | first37= Alan | last37= Cooper | first38= Kurt Werner | last38= Alt | first39= David | last39= Reich | date= 10 February 2015 | journal= bioRxiv | volume= 522 | issue= 7555 | pages= 207–211 | access-date= 5 April 2023 | biorxiv= 10.1101/013433 |arxiv= 1502.02783 |doi= 10.1038/NATURE14317 |pmid= 25731166 |pmc= 5048219 |bibcode= 2015Natur.522..207H | quote = This steppe ancestry persisted in all sampled central Europeans until at least ≈3,000 years ago, and is ubiquitous in present-day Europeans. These results provide support for the theory of a steppe origin […] of at least some of the Indo-European languages of Europe.}}
</ref><ref>
{{Cite journal | doi= 10.1038/nature14507 | pmid= 26062507 | title= Population genomics of Bronze Age Eurasia | journal= Nature | volume= 522 | issue= 7555 | pages= 167–172 | year= 2015 | last1= Allentoft | first1= Morten E. | last2= Sikora | first2= Martin | last3= Sjögren | first3= Karl-Göran | last4= Rasmussen | first4= Simon | last5= Rasmussen | first5= Morten | last6= Stenderup | first6= Jesper | last7= Damgaard | first7= Peter B. | last8= Schroeder | first8= Hannes | last9= Ahlström | first9= Torbjörn | last10= Vinner | first10= Lasse | last11= Malaspinas | first11= Anna-Sapfo | last12= Margaryan | first12= Ashot | last13= Higham | first13= Tom | last14= Chivall | first14= David | last15= Lynnerup | first15= Niels | last16= Harvig | first16= Lise | last17= Baron | first17= Justyna | last18= Della Casa | first18= Philippe | last19= Dąbrowski | first19= Paweł | last20= Duffy | first20= Paul R. | last21= Ebel | first21= Alexander V. | last22= Epimakhov | first22= Andrey | last23= Frei | first23= Karin | last24= Furmanek | first24= Mirosław | last25= Gralak | first25= Tomasz | last26= Gromov | first26= Andrey | last27= Gronkiewicz | first27= Stanisław | last28= Grupe | first28= Gisela | last29= Hajdu | first29= Tamás | last30= Jarysz | first30= Radosław | bibcode= 2015Natur.522..167A | s2cid= 4399103 | url= https://depot.ceon.pl/handle/123456789/13155 | quote = Our genomic evidence for the spread of Yamnaya people from the Pontic-Caspian steppe to both northern Europe and Central Asia during the Early Bronze Age […] corresponds well with the hypothesized expansion of the Indo-European languages.}}
</ref><ref>
{{cite journal
| url= https://www.biorxiv.org/content/early/2015/03/13/016477 | title= Eight thousand years of natural selection in Europe | first1= Iain | last1= Mathieson | first2= Iosif | last2= Lazaridis | first3= Nadin | last3= Rohland | first4= Swapan | last4= Mallick | first5= Bastien | last5= Llamas | first6= Joseph | last6= Pickrell | first7= Harald | last7= Meller | first8= Manuel A. Rojo | last8= Guerra | first9= Johannes | last9= Krause | first10= David | last10= Anthony | first11= Dorcas | last11= Brown | first12= Carles Lalueza | last12= Fox | first13= Alan | last13= Cooper | first14= Kurt W. | last14= Alt | first15= Wolfgang | last15= Haak | first16= Nick | last16= Patterson | first17= David | last17= Reich | date= 14 March 2015 | journal= bioRxiv | article-number= 016477 | access-date= 5 April 2023 | via= biorxiv.org | doi= 10.1101/016477 | doi-access= free | quote = Most present-day Europeans can be modeled as a mixture of three ancient populations related to Mesolithic hunter-gatherers (WHG), early farmers (EEF) and steppe pastoralists (Yamnaya) […].
}}
</ref>

Greek presence in the Black Sea began at least as early as the 9th century BC with [[Greek colonisation|colonies]] scattered along the Black Sea's southern coast, attracting traders and colonists due to the grain grown in the Black Sea hinterland.<ref>{{Cite book |last=Asimov |first=Isaac |title= Constantinople: The Forgotten Empire |publisher= Houghton-Mifflin |year= 1970 |page= 3}}</ref>{{request quotation|date=April 2022}}<ref>
{{cite book
 |last1 = Braun
 |first1 = Thomas
 |editor-last1 = Spiller
 |editor-first1 = Gene A.
 |orig-date = 1991
 |chapter = Ancient Mediterranean Food
 |title = The Mediterranean Diets in Health and Disease
 |date = 6 December 2012
|url = https://books.google.com/books?id=RIYpBAAAQBAJ
 |edition = reprint
 |location = New York
 |publisher = Springer
 |publication-date = 2012
 |page = 29
 |isbn = 978-1-4684-6497-9
 |access-date = 2 April 2022
|quote = The wheat trade was the reason for Greek colonization of Olbia and other Black Sea ports from c. 615 B.C. on. […] The Ukraine was the chief source of wheat imports to classical Athens: the sea route from the Crimea through the Bosporus and Dardanelles to the Aegean was Athens' lifeline.
}}
</ref>
By 500 BC, permanent Greek communities existed all around the Black Sea, and a lucrative trade network connected the entirety of the Black Sea to the wider Mediterranean. While Greek colonies generally maintained very close cultural ties to their founding [[polis]], Greek colonies in the Black Sea began to develop their own ''Black Sea Greek'' culture, known today as [[Pontic Greeks|Pontic]]. The coastal communities of Black Sea Greeks remained a prominent part of the [[Greek diaspora|Greek world]] for centuries,<ref>{{Cite book |last= King |first= Charles |title= The Black Sea |date= 18 March 2004 |publisher= Oxford University Press |isbn= 978-0-19-924161-3 |chapter=Pontus Euxinus 700BC–AD500 |doi= 10.1093/0199241619.001.0001 | url = https://books.google.com/books?id=8JlaZYxdn5sC }}</ref>{{page needed|date=April 2022}} and the realms of [[Mithridates VI Eupator|Mithridates of Pontus]], [[Roman Empire|Rome]] and [[Byzantine Empire|Constantinople]] spanned the Black Sea to include [[Crimea]]n territories.

The Black Sea became a virtual [[Ottoman Navy]] lake within five years of the [[Republic of Genoa]] losing control of the Crimean Peninsula in 1479, after which the only Western merchant vessels to sail its waters were those of [[Venice]]'s old rival [[Republic of Ragusa|Ragusa]]. The Black Sea became a [[Crimean slave trade|trade route of slaves between Crimea and Ottoman Anatolia]] via the [[Crimean–Nogai slave raids in Eastern Europe]].<ref>{{cite book |last1=Paul Robert |first1=Magocsi |title=A History of Ukraine: The Land and Its Peoples, Second Edition |date=2010 |publisher=University of Toronto Press |isbn=978-1-4426-9879-6 |pages=184–185 |url=https://books.google.com/books?id=Z0mKRsElYNkC&pg=PA184}}</ref>
[[File:BattleOfSinop 2.jpg|thumb|The destruction of the Ottoman fleet in [[Battle of Sinop]]]]
[[Imperial Russia]] became a significant Black Sea power in the late-18th century,<ref>
{{cite book
 |last1 = Birsay
 |first1 = Cem
 |editor-last1 = Volten
 |editor-first1 = Peter M. E.
 |editor-last2 = Tashev
 |editor-first2 = Blagovest
 |year = 2007
 |chapter = The Integration of Regional Efforts for Strengthening Stability Initiatives in the Wider Black Sea Area and Turkey's Position
 |title = Establishing Security and Stability in the Wider Black Sea Area: International Politics and the New and Emerging Democracies
 |url = https://books.google.com/books?id=mVQdN7Ryu4YC
 |series = Volume 26 of NATO science for peace and security series: Human and societal dynamics, ISSN 1874-6276
 |location = Amsterdam
 |publisher = IOS Press
 |page = 91
 |isbn = 978-1-58603-765-9
 |access-date = 12 April 2023
|quote = […] from the 18th century onwards, Russian ambitions fueled Turkish-Russian power conflict over the control of the Turkish Straits and the Black Sea.
}}
</ref>
occupying the littoral of [[Novorossiya]] in 1764 and [[Annexation of the Crimean Khanate by the Russian Empire|of Crimea]] in 1783. Ottoman restrictions on Black Sea navigation were challenged by the [[Black Sea Fleet]] (founded in 1783) of the [[Imperial Russian Navy]], and the Ottomans relaxed export controls after the outbreak in 1789 of the [[French Revolution]].<ref>
{{cite book
 |last1 = McGowan
 |first1 = Bruce William
 |year = 1981
 |chapter = ''Chiftlik'' agriculture, western Macedonia, 1620–1830: The economic role of the district
 |title = Economic Life in Ottoman Europe: Taxation, Trade and the Struggle for Land, 1600–1800
 |url = https://books.google.com/books?id=-xh5P2NC2FIC
 |series = Studies in Modern Capitalism, ISSN 0144-2333
 |location = Cambridge
 |publisher = Cambridge University Press
 |page = 134
 |isbn = 978-0-521-24208-0
 |access-date = 5 April 2023
|quote = A virtual cotton boom began with the onset of the American Revolutionary War in 1776, followed by a wheat boom beginning with the relaxation of Ottoman export controls following the French Revolution in 1789.
}}
</ref><ref>
{{cite book
 |last1 = Nicolle
 |first1 = David
 |author-link1 = David Nicolle
 |date = 23 March 1989
|title = The Venetian Empire 1200–1670
 |url = https://books.google.com/books?id=KV1cvgAACAAJ
 |publisher = Bloomsbury USA
 |page =
 |isbn = 978-0-85045-899-2
 |access-date = 12 April 2023
|quote =
}}
</ref>{{request quotation|date=April 2023}}<ref>{{cite book |title= Economic Life in Ottoman Europe: Taxation, Trade and the Struggle for Land, 1600–1800, Studies in Modern Capitalism |page=134 |author=Bruce McGowan |date=4 March 2010 |publisher=Cambridge University Press |isbn=978-0-521-13536-8}}</ref><ref>
Compare:
{{cite book
 | title= Economic Life in Ottoman Europe: Taxation, Trade and the Struggle for Land, 1600–1800
 | series = Studies in Modern Capitalism ISSN 0144-2333
 | publisher = Cambridge University Press | location = Cambridge
 | page= 23 |author= Bruce William McGowan |date= 1981
 | access-date = 2 April 2022 |isbn= 978-0-521-24208-0
 | url = https://books.google.com/books?id=-xh5P2NC2FIC
 | quote = […] a new group of sea-going merchants - Greek and Albanian subjects of the Porte […] flew the Russian flag after 1783 (making up the bulk of the first foreign flag commercial flotilla on the Black Sea since the departure of the Italians in the fifteenth century), taking up the slack after the collapse of French trade after 1789.
}}
</ref>

=== Modern history ===
The [[Crimean War]], fought between 1853 and 1856, saw naval engagements between the French and British allies and the forces of [[Nicholas I of Russia]]. On 2 March 1855, after the death of Nicholas I, [[Alexander II of Russia|Alexander II]] became Tsar. On 15 January 1856, the new tsar took Russia out of the war on the very unfavorable terms of the [[Treaty of Paris (1856)]], which included the loss of a naval fleet on the Black Sea, and the provision that the Black Sea was to be a [[demilitarized zone]] similar to a contemporaneous region of the [[Baltic Sea]].

==== World Wars ====
{{Campaignbox Black Sea naval campaign of World War I}}
The Black Sea was a significant naval theatre of [[Naval warfare of World War I#Black Sea|World War I]] (1914–1918) and saw both naval and land battles between 1941 and 1945 during [[Eastern Front (World War II)|World War II]]. For example, [[Sevastopol]] was obliterated by the German Wehrmacht, successfully assisted by [[Schwerer Gustav]] in the [[Siege of Sevastopol (1941–1942)]]. The Soviet naval base was one of the strongest fortifications in the world. Its site, on a deeply eroded, bare limestone promontory at the southwestern tip of the Crimea, made an approach by land forces exceedingly difficult. The high-level cliffs overlooking [[Severnaya Bay]] protected the anchorage, making an amphibious landing just as dangerous. The Soviet Navy had built upon these natural defenses by modernizing the port and installing heavy [[coastal batteries]] consisting of 180mm and 305mm re-purposed battleship guns which were capable of firing inland as well as out to sea. The artillery emplacements were protected by reinforced concrete fortifications and 9.8-inch thick armored turrets.

==== 21st century ====
During the [[Russian invasion of Ukraine]], [[Snake Island (Ukraine)|Snake Island]] was a source of contention. On 24 February 2022, two Russian navy warships [[2022 Snake Island campaign|attacked and captured Snake Island]].<ref name="MayHaveSurvived">{{cite news |last=Lamothe |first=Dan |date=26 February 2022 |title=Ukrainian border guards may have survived reported last stand on Snake Island |newspaper=[[The Washington Post]] |url=https://www.washingtonpost.com/national-security/2022/02/26/ukraine-russia-snake-island/ |url-access=subscription |access-date=27 February 2022 |archive-url=https://web.archive.org/web/20220227032528/https://www.washingtonpost.com/national-security/2022/02/26/ukraine-russia-snake-island/ |archive-date=27 February 2022}}</ref> It was subsequently bombarded heavily by Ukraine.<ref>{{Cite news |date=11 May 2022 |title=Ukraine war: Snake Island and battle for control in Black Sea |language=en-GB |work=BBC News |url=https://www.bbc.com/news/world-europe-61406808 |access-date=27 May 2022}}</ref> On 30 June 2022, Ukraine announced that it had driven Russian forces off the island.<ref name=kosiw>{{Cite news |title=Ukraine says it has pushed Russian forces from Snake Island |last=Koshiw |first=Isobel |newspaper=The Guardian |date=30 June 2022 |url= https://www.theguardian.com/world/2022/jun/30/ukraine-forces-reportedly-recapture-snake-island-in-strategic-win}}</ref>

On 14 April 2022, the flagship of the [[Black Sea Fleet]], [[Russian cruiser Moskva]] was sunk by Ukrainian missiles.<ref name=peck>{{Cite news | url=https://www.washingtonpost.com/world/2022/04/14/ukraine-russian-missile-cruiser-moskva-warship/ | title=Russia says flagship missile cruiser has sunk after explosion off coast of Ukraine | newspaper=[[The Washington Post]] |date=14 April 2022}}</ref>

As early as 29 April 2022 submarines of the Black Sea Fleet were used by Russia to bombard Ukrainian cities with [[Kalibr]] [[SLCM]]s.<ref name="reut29">{{cite news |title=Russian submarine strikes Ukraine with cruise missiles, defence ministry says |url=https://www.reuters.com/world/europe/russian-submarine-strikes-ukraine-with-cruise-missiles-defence-ministry-2022-04-29/ |publisher=Reuters |date=29 April 2022}}</ref><ref name="reut04">{{cite news |title=Russia says it fires cruise missiles from submarine, warns again on NATO arms shipments |url=https://www.reuters.com/world/europe/russia-says-it-disables-ukrainian-railway-stations-used-transport-western-2022-05-04/ |publisher=Reuters |date=4 May 2022}}</ref> The Kalibr missile was so successful that on 10 March 2023 Defense Minister [[Sergey Shoigu]] announced plans to broaden the type of ship which carried it, to include the [[corvette]] [[Steregushchiy]] and the nuclear-powered cruiser [[Russian battlecruiser Admiral Nakhimov|Admiral Nakhimov]].<ref name="msrn">{{cite news |last1=Starchak |first1=Maxim |title=Russian Navy to upgrade vessels with Kalibr cruise missiles |url=https://www.defensenews.com/naval/2023/03/10/russian-navy-to-upgrade-vessels-with-kalibr-cruise-missiles/ |publisher=Defense News |date=10 March 2023}}</ref>

On the morning of 14 March 2023, a Russian [[Su-27]] fighter jet intercepted and damaged an American [[MQ-9 Reaper]] drone, causing the latter [[2023 Black Sea drone incident|to crash into the Black Sea]]. At 13:20 on 5 May 2023 a Russian [[Su-35]] fighter jet intercepted and threatened the safety of a Polish [[L-140 Turbolet]] on a "routine [[Frontex]] patrol mission.. and performed 'aggressive and dangerous' manoeuvres".<ref name="cmrf">{{cite news |last=Mihai |first=Catalina |title=Russian fighter plane intercepts Polish aircraft over Black Sea, Romania confirms |url=https://www.euractiv.com/section/politics/news/russian-fighter-plane-intercepts-polish-aircraft-over-black-sea-romania-confirms/ |website=EURACTIV |date=8 May 2023}}</ref> The incident, which occurred "in international airspace over the Black Sea about 60km" east of Romanian airspace,<ref name="tdprj">{{cite news |title=Russian Jet Intercepts Polish Plane Over Black Sea: Romania |url=https://www.thedefensepost.com/2023/05/07/russian-jet-intercepts-polish-plane/ |agency=AFP |website=The Defense Post |date=7 May 2023}}</ref> "caused the crew of five Polish border guards to lose control of the plane and lose altitude."<ref name="pbgdw">{{cite news |title=Poland Border Guard says patrol intercepted by Russian jet |url=https://www.dw.com/en/poland-border-guard-says-patrol-intercepted-by-russian-jet/a-65541526 |agency=AFP, dpa |website=Deutsche Welle |date=7 May 2023}}</ref>

As of January 2025, neither Ukraine nor Russia control the Black Sea, making it contested, claims [[Estonian Navy]] Commander Ivo Värk. "The entire Black Sea can currently be seen as a contested maritime area where both sides have some room for action,". This room is greater near the coasts, where both sides benefit from air defense systems, sea mines, and various land-based weaponry. Ships only move out for specific operations to prevent excessive risks. He also noted that both parties operate gas drilling platforms equipped with surveillance devices to monitor the situation, but that those platforms often change hands.<ref>{{Cite web |title=Estonian Navy Commander: Black Sea a Disputed Area in Naval Warfare - Oj |url=https://odessa-journal.com/commander-of-the-estonian-navy-neither-russia-nor-ukraine-dominates-in-the-black-sea |access-date=2025-01-06 |website=odessa-journal.com |language=en}}</ref><ref>{{Cite web |date=6 January 2025 |title=Kreml meldet Einnahme der Stadt Kurachowe |url=https://www.n-tv.de/politik/10-13-Beide-Seiten-haben-keine-Kontrolle-ueber-Schwarzes-Meer--article23143824.html |url-status=live |archive-url=https://web.archive.org/web/20250106093103/https://www.n-tv.de/politik/10-13-Beide-Seiten-haben-keine-Kontrolle-ueber-Schwarzes-Meer--article23143824.html |archive-date=6 January 2025 |access-date=6 January 2025 |website=[[n-tv]] |language=de}}</ref>

== Economy and politics ==
{{More citations needed section |date=February 2024}}
[[File:Widok na Jałtę ze statku 06.JPG|thumb|[[Yalta]], Crimea]]
[[File:Amasra,_Turkey,_Castle,_view_from_the_island.jpg|thumb|[[Amasra]], Turkey, is located on a small island in the Black Sea.]]The Black Sea plays an integral part in the connection between Asia and Europe.<ref>{{Cite book|title=Eurasian Slavery, Ransom and Abolition in World History, 1200–1860|date=9 March 2016|publisher=Routledge|doi=10.4324/9781315580777|isbn=978-1-317-14002-3|url=https://www.recensio.net/r/6b7c562f59144b58a5824c7a90b84c47 |editor-last=Witzenrath|editor-first=Christoph}}</ref> In addition to sea ports and fishing, key activities include hydrocarbons exploration for oil and natural gas, and tourism.
According to [[NATO]], the Black Sea is a strategic corridor that provides [[smuggling]] channels for moving legal and illegal goods including drugs, radioactive materials, and counterfeit goods that can be used to finance terrorism.<ref name="Black Sea Security">{{cite news | url=https://books.google.com/books?id=EfNxWxwDX0EC&q=traffic+on+the+black+sea&pg=PA4| title=Black Sea Security | work=NATO Advanced Research Workshop | date=2010 | isbn=978-1-60750-636-2 | access-date=31 December 2010 | agency=NATO| last1=Houston | first1=Fiona | last2=Duncan Wood | first2=W. | last3=Robinson | first3=Derek M. }}</ref>

=== Navigation ===
According to an [[International Transport Workers' Federation]] 2013 study, there were at least 30 operating merchant [[seaport]]s in the Black Sea (including at least 12 in [[Ukraine]]).<ref name="Черное море признано">{{cite news | url=http://www.blackseanews.net/read/64439 | title=Черное море признано одним из самых неблагоприятных мест для моряков | work=[[International Transport Workers' Federation]] | date=27 May 2013 | access-date=20 September 2013 | agency=BlackSeaNews}}</ref> There were also around 2,400 commercial vessels operating in the Black Sea.<ref name="Черное море признано" />

=== Fishing ===
{{See also|Fishing in Turkey}}
The Turkish commercial fishing fleet catches around 300,000 tons of [[European anchovy|anchovies]] per year. The fishery is carried out mainly in winter, and the highest portion of the stock is caught in November and December.<ref>[http://hamsi.ims.metu.edu.tr/sunumlar/6-Anchovy_Medias_2013.pdf "Turkish Black Sea Acoustic Surveys: Winter distribution of anchovy along the Turkish coast".] Serdar Sakinan. Middle East Technical University – Institute of Marine Sciences. {{Webarchive|url=https://web.archive.org/web/20190807230651/http://hamsi.ims.metu.edu.tr/sunumlar/6-Anchovy_Medias_2013.pdf |date=7 August 2019 }}.</ref>

=== Hydrocarbon exploration ===
{{See also|Blue Stream|South Stream|TurkStream}}The Black Sea contains oil and natural gas resources but exploration in the sea is incomplete. {{As of|2017}}, 20 wells are in place. Throughout much of its existence, the Black Sea has had significant oil and gas-forming potential because of significant inflows of sediment and nutrient-rich waters. However, this varies geographically. For example, prospects are poorer off the coast of Bulgaria because of the large influx of sediment from the Danube which obscured sunlight and diluted organic-rich sediments. Many of the discoveries to date have taken place offshore of Romania in the Western Black Sea and only a few discoveries have been made in the Eastern Black Sea.{{Citation needed|date=July 2025}}

During the [[Eocene]], the [[Paratethys]] Sea was partially isolated and sea levels fell. During this time sand shed off the rising Balkanide, Pontide and Caucasus mountains trapped organic material in the Maykop Suite of rocks through the [[Oligocene]] and early [[Miocene]]. Natural gas appears in rocks deposited in the Miocene and Pliocene by the paleo-Dnieper and paleo-Dniester rivers, or in deep-water Oligocene-age rocks. Serious exploration began in 1999 with two deep-water wells, Limanköy-1 and Limanköy-2, drilled in Turkish waters. Next, the HPX (Hopa)-1 deepwater well targeted late Miocene sandstone units in Achara-Trialeti fold belt (also known as the Gurian fold belt) along the Georgia-Turkey maritime border. Although geologists inferred that these rocks might have hydrocarbons that migrated from the Maykop Suite, the well was unsuccessful. No more drilling happened for five years after the HPX-1 well. In 2010, Sinop-1 targeted carbonate reservoirs potentially charged from the nearby Maykop Suite on the Andrusov Ridge, but the well-struck only Cretaceous volcanic rocks. Yassihöyük-1 encountered similar problems.{{Citation needed|date=July 2025}}

Other Turkish wells, Sürmene-1 and Sile-1 drilled in the Eastern Black Sea in 2011 and 2015 respectively tested four-way closures above Cretaceous volcanoes, with no results in either case. A different Turkish well, Kastamonu-1 drilled in 2011 did successfully find thermogenic gas in Pliocene and Miocene shale-cored anticlines in the Western Black Sea. A year later in 2012, Romania drilled Domino-1 which struck gas prompting the drilling of other wells in the Neptun Deep. In 2016, the Bulgarian well Polshkov-1 targeted Maykop Suite sandstones in the Polshkov High and Russia is in the process of drilling Jurassic carbonates on the Shatsky Ridge as of 2018.{{sfn|Simmons|Tari|Okay|2018|p=10-12}}

In August 2020, [[Turkey]] found {{Convert|320|e9m3||abbr=off}} of natural gas in the biggest ever discovery in the Black Sea, and hoped to begin production in the [[Sakarya Gas Field]] by 2023. The sector is near where [[Romania]] has also found gas reserves.<ref>{{cite news |author=Selcan Hacaoglu |author2=Vanessa Dezem |author3=Cagan Koc|date=21 August 2020|title=Erdogan Unveils Biggest Ever Black Sea Natural Gas Discovery|publisher=[[Bloomberg News]]|url=https://www.bloomberg.com/news/articles/2020-08-21/all-eyes-on-erdogan-as-reports-of-black-sea-energy-find-mount |url-access=subscription |access-date=22 August 2020}}</ref>

=== Trans-sea cooperation ===
{{Main|Black Sea Euroregion|Superior Prut and Lower Danube|Black Sea Games|Organization of the Black Sea Economic Cooperation}}

=== Urban areas ===
{| class="wikitable sortable" style="text-align:center;"
|+ Most populous urban areas along the Black Sea
|-
! scope="col" | City
! scope="col" class=unsortable| Image
! scope="col" | Country
! scope="col" | Region/county
! scope="col" | Population (urban)
|-
! scope="row" | [[Istanbul]]
| [[File:Istanbul, Turkey Bosporus.jpg|border|135px]]
| {{TUR}}||[[Istanbul Province|Istanbul]]||15,340,111
|-
! scope="row" | [[Odesa]]
| [[File:Будинок театру опери та балету, Одеса DJI 0023.jpg|border|135px]]
| {{UKR}}||[[Odesa Oblast|Odesa]]||1,003,705
|-
! scope="row" | [[Samsun]]
| [[File:Samsun - panoramio (11).jpg|border|135px]]
| {{TUR}}||[[Samsun Province|Samsun]]||639,930<ref name=citypop>{{cite web |url=https://www.citypopulation.de/en/turkey/cities/ |title=Turkey: Provinces and Major Cities |website=City Population |date=13 February 2023 |access-date=23 January 2024 }}</ref>
|-
! scope="row" | [[Varna, Bulgaria|Varna]]
| [[File:Varna_Plage.JPG|border|135px]]
| {{BGR}}||[[Varna Province|Varna]]||500,076
|-
! scope="row" | [[Constanța]]
| [[File:Costanza porto - panoramio.jpg|border|135px]]
| {{ROU}}||[[Constanța County|Constanța]]||491,498<ref>{{cite web|url=http://www.analizeeconomice.ro/2016/03/cat-crescut-populatia-in-principalele.html|title=Cât a crescut populația în principalele zone metropolitane ale țării în ultimele două decenii|website=www.analizeeconomice.ro}}</ref>
|-
! scope="row" | [[Sevastopol]]
| [[File:Sevastopol_Crimea-5243.jpg|border|135px]]
| [[Political status of Crimea|disputed]]:<br />{{UKR}} (''[[de jure]]'')<br />{{RUS}} (''[[de facto]]'')|| [[City with special status]] /<br />[[Federal cities of Russia|Federal city]]||379,200
|-
! scope="row" | [[Sochi]]
| [[File:Sochi_harbour.jpg|border|135px]]
| {{RUS}}||[[Krasnodar Krai]]||343,334
|-
! scope="row" | [[Trabzon]]
| [[File:Trabzon_-_panoramio_(2).jpg|border|135px]]
| {{TUR}}||[[Trabzon Province|Trabzon]]||293,661<ref name=citypop/>
|-
! scope="row" | [[Novorossiysk]]
| [[File:Novo-2010-08-27-043.jpg|border|135px]]
| {{RUS}}||[[Krasnodar Krai]]||241,952
|-
! scope="row" | [[Burgas]]
| [[File:Burgas Juni2012 Hafen und der Burgas-See.JPG|border|135px]]
| {{BGR}}||[[Burgas Province|Burgas]]||223,902
|-
! scope="row" | [[Batumi]]
| [[File:US Navy 200623-N-O901-0001 USS Porter (DDG 78) in Batumi, Georgia on June 23, 2020.jpg|border|135px]]
| {{GEO}}||[[Autonomous Republic of Adjara|Adjara]]||204,156<ref>{{cite web |url=http://www.batumi.ge/en/ |title=Batumi City Hall website |access-date=10 August 2017 |archive-date=21 August 2015 |archive-url=https://web.archive.org/web/20150821170635/http://www.batumi.ge/en/ }}</ref>
|-
! scope="row" | [[Ordu]]
| [[File:Ordu,_Turkey.JPG|border|135px]]
| {{TUR}}||[[Ordu]]||190,425<ref name=citypop/>
|-
! scope="row" | [[Kerch]]
| [[File:Kerch ObeliskOfGlory.jpg|border|135px]]
| [[Political status of Crimea|disputed]]:<br />{{UKR}} (''[[de jure]]'')<br />{{RUS}} (''[[de facto]]'')|| [[Autonomous Republic of Crimea]] /<br />[[Republic of Crimea (Russia)|Republic of Crimea]]||149,566
|}

=== Tourism ===
{{See also|Romanian Black Sea resorts|Caucasian Riviera|Bulgarian Black Sea Coast|Black Sea Region, Turkey}}[[File:Zatoka_Beach.jpg|thumb|Black Sea beach in Zatoka, Ukraine]]
In the years following the end of the [[Cold War]], the popularity of the Black Sea as a [[tourism|tourist]] destination steadily increased. Tourism at Black Sea resorts became one of the region's growth industries.<ref>{{cite web|title=Bulgarian Sea Resorts|url=http://www.bulgariansearesorts.com|archive-url=https://web.archive.org/web/20200427174751/http://www.bulgariansearesorts.com/|archive-date=27 April 2020|access-date=2 February 2007}}</ref>

The following is a list of notable Black Sea [[resort]] towns:

{{div col |colwidth=10em}}
* [[2 Mai]] (Romania)
* [[Agigea]] (Romania)
* [[Ahtopol]] (Bulgaria)
* [[Amasra]] (Turkey)
* [[Anaklia]] (Georgia)
* [[Anapa]] (Russia)
* [[Albena]] (Bulgaria)
* [[Alupka]] (Crimea, Ukraine/Russia <small>(disputed)</small>)
* [[Alushta]] (Crimea, Ukraine/Russia <small>(disputed)</small>)
* [[Balchik]] (Bulgaria)
* [[Batumi]] (Georgia)<ref>Postcard from the Silk Road – Batumi...([http://www.znadwiliiwilno.lt/wp-content/uploads/2020/04/Znad-Wilii-57m.pdf] {{Webarchive|url=https://web.archive.org/web/20200604130631/http://www.znadwiliiwilno.lt/wp-content/uploads/2020/04/Znad-Wilii-57m.pdf |date=4 June 2020 }})</ref>
* [[Burgas]] (Bulgaria)
* [[Byala, Varna Province|Byala]] (Bulgaria)
* [[Cap Aurora]] (Romania)
* [[Chakvi]] (Georgia)
* [[Constanța]] (Romania)
* [[Saints Constantine and Helena, Bulgaria|Constantine and Helena]] (Bulgaria)
* [[Corbu, Constanța|Corbu]] (Romania)
* [[Costinești]] (Romania)
* [[Eforie]] (Romania)
* [[Emona, Bulgaria|Emona]] (Bulgaria)
* [[Feodosia]] (Crimea, Ukraine/Russia <small>(disputed)</small>)
* [[Foros, Crimea|Foros]] (Crimea, Ukraine/Russia <small>(disputed)</small>)
* [[Gagra]] (Abkhazia/Georgia{{efn|name=Abkhazia}})
* [[Gelendzhik]] (Russia)
* [[Giresun]] (Turkey)
* [[Golden Sands]] (Bulgaria)
* [[Gonio (settlement)|Gonio]] (Georgia)
* [[Gudauta]] and subsequently the [[Gudauta Bay]] (Abkhazia/Georgia{{efn|name=Abkhazia}})
* [[Gurzuf]] (Crimea, Ukraine/Russia <small>(disputed)</small>)
* [[Hopa]] (Artvin, Turkey)
* [[Jupiter, Romania|Jupiter]] (Romania)
* [[Resort of Kamchiya|Kamchia]] (Bulgaria)
* [[Kavarna]] (Bulgaria)
* [[Kiten, Burgas Province|Kiten]] (Bulgaria)
* [[Kobuleti]] (Georgia)
* [[Koktebel]] (Crimea, Ukraine/Russia <small>(disputed)</small>)
* [[Lozenets, Burgas Province|Lozenetz]] (Bulgaria)
* [[Mamaia]] (Romania)
* [[Mangalia]] (Romania)
* [[Năvodari]] (Romania)
* [[Neptun, Romania|Neptun]] (Romania)
* [[Nesebar]] (Bulgaria)
* [[Novorossiysk]] (Russia)
* [[Obzor]] (Bulgaria)
* [[Odesa]] (Ukraine)
* [[Olimp, Romania|Olimp]] (Romania)
* [[Ordu]] (Turkey)
* [[Pitsunda| Pitsunda/Bichvinta]] (Abkhazia/Georgia{{efn|name=Abkhazia}})
* [[Pomorie]] (Bulgaria)
* [[Primorsko]] (Bulgaria)
* [[Rize]] (Turkey)
* [[Rusalka, Bulgaria|Rusalka]] (Bulgaria)
* [[Samsun]] (Turkey)
* [[Saturn, Romania|Saturn]] (Romania)
* [[Şile]] (Turkey)
* [[Sinop, Turkey|Sinop]] (Turkey)
* [[Skadovsk]] (Ukraine)
* [[Sochi]] (Russia)
* [[Sozopol]] (Bulgaria)
* [[Sudak]] (Crimea, Ukraine/Russia <small>(disputed)</small>)
* [[Sulina]] (Romania)
* [[Sunny Beach]] (Bulgaria)
* [[Sveti Vlas]] (Bulgaria)
* [[Trabzon]] (Turkey)
* [[Tsikhisdziri]] (Georgia)
* [[Tuapse]] (Russia)
* [[Ureki]] (Georgia)
* [[Vama Veche]] (Romania)
* [[Varna, Bulgaria|Varna]] (Bulgaria)
* [[Venus, Romania|Venus]] (Romania)
* [[Yalta]] (Crimea, Ukraine/Russia <small>(disputed)</small>)
* [[Yevpatoria]] (Crimea, Ukraine/Russia <small>(disputed)</small>)
* [[Zonguldak]] (Turkey){{div col end}}

=== Modern military use ===
[[File:USS Yorktown collision.jpg|thumb|Soviet frigate ''[[Ukrainian frigate Dnipropetrovsk|Bezzavetny]]'' (right) bumping the [[USS Yorktown (CG-48)|USS ''Yorktown'']] during the [[1988 Black Sea bumping incident]]]]
[[File:Boat U170 Skadovsk 2012 G1.jpg|thumb|[[Ukrainian Navy]] artillery boat U170 in the [[Bay of Sevastopol]]]]
The [[Montreux Convention Regarding the Regime of the Straits|1936 Montreux Convention]] provides for free passage of civilian ships between the international waters of the Black and the Mediterranean seas. However, a single country (Turkey) has complete control over the straits connecting the two seas. Military ships are categorized separately from civilian vessels and can pass through the straits only if the ship belongs to a Black Sea country. Other military ships have the right to pass through the straits if they are not in a war against Turkey and if they stay in the Black Sea basin for a limited time. The 1982 amendments to the [[Montreux Convention Regarding the Regime of the Straits|Montreux Convention]] allow Turkey to close the straits at its discretion in both war and peacetime.<ref>{{cite web |url=http://www.yeniansiklopedi.com/bogazlar-sorunu/ |archive-url=https://web.archive.org/web/20131212082536/http://www.yeniansiklopedi.com/bogazlar-sorunu/ |archive-date=12 December 2013 |title=Montreaux and the Bosporus Problem |language=tr}}</ref>

The Montreux Convention governs the passage of vessels between the Black, Mediterranean, and Aegean seas and the presence of military vessels belonging to non-[[littoral]] states in the Black Sea waters.<ref>{{cite web |url=http://www.karalahana.com/kafkasya-politika-strateji/Montro_TR.pdf |title=Montreaux Convention and Turkey (pdf) |archive-url=https://web.archive.org/web/20130319212703/http://www.karalahana.com/kafkasya-politika-strateji/Montro_TR.pdf |archive-date=19 March 2013}}</ref>

The Russian [[Black Sea Fleet]] has its official primary headquarters and facilities in the city of [[Sevastopol]] ([[Sevastopol Naval Base]]).<ref>{{cite news |title=HMS Defender: What will be the fallout from Black Sea incident? |url=https://www.bbc.com/news/world-europe-57589366 |publisher=BBC News |date=23 June 2021}}</ref>

The Soviet hospital ship {{ship||Armenia|ship|2}} was sunk on 7 November 1941 by German aircraft while evacuating civilians and wounded soldiers from [[Crimea]]. It has been estimated that approximately 5,000 to 7,000 people were killed during the sinking, making it one of the deadliest [[List of maritime disasters in the 20th century|maritime disasters]] in history. There were only eight survivors.<ref>{{cite web|url=http://www.wrecksite.eu/wreck.aspx?17800 |title=MV Armenia (Армения) (+1941) |website=Wrecksite.eu |date=27 October 2014 }}</ref>

In December 2018, the [[Kerch Strait incident]] occurred, in which the Russian navy and coast guard took control of three Ukrainian vessels as the ships were trying to transit from the Black Sea into the [[Sea of Azov]].<ref>{{cite web |url=https://www.theguardian.com/world/2018/dec/04/ukraine-ports-partially-unblocked-by-russia-says-kiev |title=Ukraine's ports partially unblocked by Russia, says Kiev |agency=Associated Press |date=4 December 2018 |work=[[The Guardian]]}}</ref>

In April 2022, during the Russian invasion of Ukraine, the [[Russian cruiser Moskva]] was sunk in the western Black Sea by sea-skimming [[R-360 Neptune|Neptune]] missiles of the [[Armed Forces of Ukraine|Ukrainian Armed Forces]]<ref>{{cite web |date=15 April 2022 |title=Prized Russian Ship Was Hit by Missiles, U.S. Officials Say |url=https://www.nytimes.com/2022/04/15/us/politics/russia-moskva-ship-sunk-ukraine.html |url-access=limited |work=[[The New York Times]] |agency=New York Times}}</ref> while the Russians claimed that an onboard fire had caused munitions to explode and damage the ship extensively.<ref>{{Cite news |date=14 April 2022 |title=Ukraine claims it hit a Russian warship with a missile strike. Russia says otherwise. |work=CNN |url=https://edition.cnn.com/europe/live-news/ukraine-russia-putin-news-04-14-22#h_b86aab890c25dec71a5bc96c478076b2}}</ref> She was the largest ship to be lost in naval combat in Europe since [[World War II]].<ref>{{Cite news |date=15 April 2022 |title=Russian warship: Moskva sinks in Black Sea |language=en-GB |work=BBC News |url=https://www.bbc.com/news/world-europe-61114843 |access-date=15 June 2022}}</ref>

In late 2023, Russia announced plans to build a naval base on the Black Sea coast of [[Abkhazia]].<ref name="abkhazia_2023_10_05_reuters">[https://www.reuters.com/world/europe/russia-plans-naval-base-black-sea-coast-breakaway-georgian-region-izvestiya-2023-10-05/ "Russia plans naval base in Abkhazia, triggering criticism from Georgia"] 5 October 2023, [[Reuters]], retrieved 12 January 2024</ref><ref name="breakaway_2023_10_05_politico">[https://www.politico.eu/article/vladimir-putin-russia-black-sea-abkhazia-plans-to-build-naval-base-in-georgias-breakaway-region-as-it-pulls-vessels-from-sevastopol-base/ "Russia to build naval base in breakaway Georgia region"] 5 October 2023, ''[[Politico]]'' (Politico.eu), retrieved 12 January 2024</ref><ref name="alarms_2023_12_12_bbc">[https://www.bbc.com/news/world-europe-67625450 "Russia's new Black Sea naval base alarms Georgia,"] 12 December 2023, [[BBC News]], retrieved 12 January 2024</ref>{{efn|name=Abkhazia}}

== See also ==
{{Portal|left=yes|Water}}
* [[1927 Crimean earthquakes]]
* [[Kerch Strait]]
* [[Regions of Europe]]
* [[Sea of Azov]]
* [[Laz people]]
* [[Lazistan Sanjak]]
* [[Lazistan]]

== Notes and references ==
=== Informational notes ===
{{notelist}}

=== Citations ===
{{Reflist}}

=== General and cited references ===
{{Refbegin}}
* [[Neal Ascherson]] (1996). ''Black Sea''. Vintage. {{ISBN|0-09-959371-8}}.
* {{cite book |last1=Dimitrov |first1=Petko |last2=Dimitrov |first2=Dimitar |year=2004 |title=The Black Sea, the Flood and the Ancient Myths |url=https://www.researchgate.net/publication/290938137 |publisher=Varna |isbn=978-954-579-335-6|page= 91}}
* {{cite book |last=Dimitrov |first=Dimitar |date=August 2010 |title=Geology and Non-traditional Resources of the Black Sea |url=https://www.researchgate.net/publication/311582414 |archive-url=https://web.archive.org/web/20220209034651/https://www.researchgate.net/publication/311582414_Geology_and_Non-traditional_resources_of_the_Black_Sea |archive-date=9 February 2022 |publisher=[[VDM Publishing|LAP (Lambert Academic Publishing)]] |doi=10.13140/RG.2.2.20631.88486 |isbn=978-3-8383-8639-3}}
* Ghervas, Stella (2008). "Odessa et les confins de l'Europe: un éclairage historique", in Stella Ghervas et François Rosset (ed.), ''Lieux d'Europe. Mythes et limites''. Paris: Editions de la Maison des sciences de l'homme. pp.&nbsp;107–124. {{ISBN|978-2-7351-1182-4}}.
* {{cite book |last1 = Ghervas |first1 = Stella|year = 2017 |doi=10.1017/9781108399722.010|chapter = The Black Sea|title = Oceanic Histories|pages = 234–266 |editor1-last=Armitage|editor1-first=D.|editor2-last=Bashford|editor2-first=S.|chapter-url=https://www.cambridge.org/core/books/oceanic-histories/black-sea/3BED782610F53D0F89ED0BDC1C99F442|url=https://www.cambridge.org/core/books/oceanic-histories/7BDD2F35C5E019DB8D3228DE4380B457|location=Cambridge |publisher=Cambridge University Press |isbn=978-1-1083-9972-2}}
* [[Charles King (professor of international affairs)|King, Charles]] (2004). ''The Black Sea: A History''. {{ISBN|0-19-924161-9}}.
* Ryan, William, and Walter Pitman (1999). ''Noah's Flood''. {{ISBN|0-684-85920-3}}.
* {{Encyclopaedia Iranica | last = Schmitt | first = Rüdiger | author-link = Rüdiger Schmitt | article = Black Sea | url = http://www.iranicaonline.org/articles/black-sea | volume = 4 | fascicle = 3 | pages = 310–313 }}
* Schmitt, Rüdiger (1996). "Considerations on the Name of the Black Sea", in: ''Hellas und der griechische Osten''. Saarbrücken. pp.&nbsp;219–224.
* {{cite journal |author=West, Stephanie |date=October 2003 |title='The Most Marvellous of All Seas': The Greek Encounter with the Euxine |journal=Greece & Rome |volume=50 |issue=2 |pages=151–167 |doi=10.1093/gr/50.2.151 |jstor=3567890}}
{{Refend}}

== External links ==
{{commons category|Black Sea}}
{{Wikivoyage|Black Sea}}

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* [https://web.archive.org/web/20080207093027/http://www.blacksea-online.com/eng/ Space Monitoring of the Black Sea Coastline and Waters]
* [https://web.archive.org/web/20081226115914/http://www.mapofukraine.net/crimean_peninsula/black_sea/crimea_black_sea_coast.html Pictures of the Black sea coast all along the Crimean peninsula]
* [https://web.archive.org/web/20131110111415/http://www.grid.unep.ch/bsein/ Black Sea Environmental Internet Node]
* [https://web.archive.org/web/20141006150829/http://sealevel.ns.ca/igcp521/ Black Sea-Mediterranean Corridor during the last 30 ky: UNESCO IGCP 521 WG12]

{{List of seas}}
{{Marginal seas of the Atlantic Ocean}}
{{Countries bordering the Black Sea}}
{{Georgia (country) topics}}

{{Authority control}}

[[Category:Black Sea| ]]
[[Category:Seas of the Mediterranean Sea]]
[[Category:Anoxic waters]]
[[Category:Back-arc basins]]<!-- formed as such, but long extinct -->
[[Category:European seas]]
[[Category:Seas of Russia]]
[[Category:Seas of Turkey]]
[[Category:Seas of Ukraine]]
[[Category:Bodies of water of Bulgaria]]
[[Category:Bodies of water of Georgia (country)]]
[[Category:Bodies of water of Romania]]
[[Category:Bodies of water of Crimea]]
[[Category:Bulgaria–Romania border]]
[[Category:Bulgaria–Turkey border]]
[[Category:Georgia (country)–Russia border]]
[[Category:Georgia (country)–Turkey border]]
[[Category:Romania–Ukraine border]]
[[Category:Russia–Ukraine border]]
[[Category:Seas of the Atlantic Ocean]]
[[Category:Seas of Asia]]
[[Category:Geography of West Asia]]