View source for Pole of inaccessibility

{{Short description|Geographic location}}
{{For|the Antarctic research station|Pole of Inaccessibility research station}}
{{Use dmy dates|date=November 2022}}

[[File:Distancia a la costa.png|thumb|upright=1.8|Map of distance to the nearest coastline<ref name="Garcia2007" /> (including oceanic islands, but not lakes) with red spots marking the poles of inaccessibility of main [[landmass]]es, [[Great Britain]], and the [[Iberian Peninsula]], and a blue dot marking the oceanic pole of inaccessibility. Thin [[isolines]] are {{convert|250|km|abbr=on}} apart; thick lines {{convert|1000|km|abbr=on}}. [[Mollweide projection]].]]
In [[geography]], a '''pole of inaccessibility''' is the farthest (or most difficult to reach) location in a given landmass, sea, or other topographical feature, starting from a given boundary, relative to a given criterion. A geographical criterion of inaccessibility marks a location that is the most challenging to reach according to that criterion. Often it refers to the most distant point from the [[coastline]], implying the farthest point into a [[landmass]] from the shore, or the farthest point into a [[body of water]] from the shore. In these cases, a pole of inaccessibility is the center of a maximally large circle that can be drawn within an area of interest only touching but not crossing a coastline. Where a coast is imprecisely defined, the pole will be similarly imprecise.

==Northern pole of inaccessibility==
[[File:Cực bất khả tiếp cận Bắc - Northern pole of inaccessibility.jpg|thumb|Northern pole of inaccessibility]]

The northern pole of inaccessibility, sometimes known as the Arctic pole, is located on the [[Arctic Ocean]] [[pack ice]] at a distance farthest from any landmass. The original position was wrongly believed to lie at 84°3′N 174°51′W. It is not clear who first defined this point, but it may have been Sir [[Hubert Wilkins]], who wished to traverse the Arctic Ocean by [[aircraft]] in 1927. He was finally successful in 1928. In 1968 [[Wally Herbert|Sir Wally Herbert]] came very close to reaching what was then considered to be the position by dogsled, but by his own account, ''Across the Top of the World'', did not make it due to the flow of sea ice.<ref>{{Cite book |last=Herbert |first=Wally |author-link=Wally Herbert |year=1971 |title=Across the Top of the World: The Last Great Journey on Earth |url=https://archive.org/details/acrosstopofwor00herb/mode/2up |url-access=registration |location=New York |publisher=G. P. Putnam |page=[https://archive.org/details/acrosstopofwor00herb/page/176/mode/2up 177–178] |lccn=70136800 |oclc=1023774535 |access-date=19 August 2024 |via=Internet Archive}}</ref> In 1986, an expedition of Soviet polar scientists led by [[Dmitry Shparo]] claimed to reach the original position by foot during a polar night.{{Citation needed|date=October 2021}}

In 2005, explorer [[Jim McNeill, Polar Explorer|Jim McNeill]] asked scientists from The [[National Snow and Ice Data Center]] and [[Scott Polar Research Institute]] to re-establish the position using modern GPS and satellite technology. This was published as a paper in the ''Polar Record'', [[Cambridge University Press]] in 2013.<ref name="Rees2014" /> McNeill launched his own, unsuccessful attempt to reach the new position in 2006, while measuring the depth of sea-ice for [[NASA]].<ref>{{cite news|date=20 February 2006|title=Explorer set for historic Arctic adventure|publisher=[[BBC]]|url=http://news.bbc.co.uk/1/hi/sci/tech/4731672.stm|url-status=live|access-date=10 November 2010|archive-url=https://web.archive.org/web/20060527193017/http://news.bbc.co.uk/1/hi/sci/tech/4731672.stm|archive-date=27 May 2006}}</ref> In 2010 he and his [[Ice Warrior Project|Ice Warrior]] team were thwarted again by the poor condition of the sea ice.<ref>{{cite web|last=Becker|first=Kraig|date=10 February 2010|title=North Pole 2010: Expedition to the Pole of Inaccessibility Is Postponed|url=https://adventureblog.net/2010/02/north-pole-2010-expedition-to-pole-of.html|url-status=live|archive-url=https://web.archive.org/web/20161013054113/http://theadventureblog.blogspot.com/2010/02/north-pole-2010-expedition-to-pole-of.html|archive-date=13 October 2016|access-date=10 November 2016|work=theadventureblog.blogspot.com|publisher=The Adventure Blog}}</ref>

The new position lies at {{Coord|85|48|N|176|9|W|name=North Pole of Inaccessibility (NPRI)}}, {{convert|1008|km}} from the three closest landmasses: [[Henrietta Island]] in the [[De Long Islands]], at [[Arctic Cape]] on [[Severnaya Zemlya]], and on [[Ellesmere Island]]. It is over {{convert|200|km}} from the originally accepted position.<ref>{{Cite journal|last=Duhaime-Ross|first=Arielle|date=15 October 2013|title=A New Race to Earth's End|journal=Scientific American|volume=309|issue=16|pages=16|doi=10.1038/scientificamerican1113-16a|pmid=24283006}}</ref> Due to constant motion of the pack ice, no permanent structure can exist at this pole. On 12 September 2024, the French icebreaking cruise ship ''[[Le Commandant Charcot]]'' became the first ship to reach the Northern Pole of Inaccessibility.<ref>{{cite web|url=https://www.marineinsight.com/shipping-news/worlds-only-luxury-icebreaker-becomes-first-ship-to-reach-north-pole-of-inaccessibility/|title=World's Only Luxury Icebreaker Becomes First Ship To Reach North Pole Of Inaccessibility|date=24 September 2024|accessdate=24 September 2024|website=Marine Insight}}</ref>

==Southern pole of inaccessibility==
[[File:Southern Pole of Inaccessibility Henry Cookson team n2i.jpg|thumb|The old Soviet Pole of Inaccessibility Station, revisited by [[Henry Cookson#Team N2i|Team N2i]] on 19 January 2007]]
The southern pole of inaccessibility is the point on the [[Antarctica|Antarctic]] continent most distant from the [[Southern Ocean]]. A variety of coordinate locations have been given for this pole. The discrepancies are due to the question of whether the "coast" is measured to the grounding line or the edges of ice shelves, the difficulty of determining the location of the "solid" coastline, the movement of ice sheets and improvements in the accuracy of survey data over the years, as well as possible topographical errors.

The point commonly referred to as the pole of inaccessibility is the site of the [[Pole of inaccessibility (Antarctic research station)|Soviet Union research station]] mentioned below, which was constructed at {{Coord |82 |6 |S |54 |58|E|name=Pole of Inaccessibility (WMO)}}<ref name = meteorological>{{Cite web|url=http://www.wmo.int/pages/prog/www/Antarctica/Ant-cat-Rus-Fed.html|title=Catalogue of Russian Antarctic Meteorological data 1994 |last=Danilov|first=A. I.|publisher=[[World Meteorological Organization]]|access-date=10 November 2016 |url-status=dead |archive-url=https://web.archive.org/web/20160513160724/http://www.wmo.int/pages/prog/www/Antarctica/Ant-cat-Rus-Fed.html |year=1994 |archive-date=13 May 2016 }}</ref> (though some sources give {{Coord|83|6|S|54|58|E|name=South Pole of Inaccessibility (IPHC)}}<ref>{{Cite web |url=http://www.polarheritage.com/index.cfm/Sitelist01up|title=Historic Sites & Monuments in Antarctica|date=2016|publisher=International Polar Heritage Committee|access-date=10 November 2016|url-status=live|archive-url=https://web.archive.org/web/20070929161454/http://www.polarheritage.com/index.cfm/Sitelist01up|archive-date=29 September 2007}}</ref>). This lies {{convert|1301|km |abbr= on}} from the [[South Pole]], at an [[elevation]] of {{convert|3,718|m|abbr=on}}. Using different criteria, the [[Scott Polar Research Institute]] locates this pole at {{Coord|85|50|S|65|47|E|name=South Pole of Inaccessibility (SPRI)}}.<ref>{{Cite web|url=http://www.spri.cam.ac.uk/resources/infosheets/23.html|title=Polar Information Sheets|last=Headland|first=R. K.|date=1996|publisher=[[Scott Polar Research Institute]], [[University of Cambridge]]|access-date=10 November 2016|url-status=live|archive-url=https://web.archive.org/web/20160528131216/http://www.spri.cam.ac.uk/resources/infosheets/23.html|archive-date=28 May 2016}}</ref>

Using recent datasets and cross-confirmation between the adaptive gridding and B9-Hillclimbing<ref name="Barnes2019"/> methods discussed below, Rees et al. (2021)<ref name="Rees2021"/> identify two poles of inaccessibility for Antarctica: an "outer" pole defined by the edge of Antarctica's floating ice shelves and an "inner" pole defined by the grounding lines of these sheets. They find the Outer pole to be at {{Coord|83.904|S|64.890|E|name=Antarctia's Outer Pole of Inaccessibility}}, {{Convert|1590.4|km|abbr=on}} from the ocean, and the Inner pole to be at {{Coord|83.610|S|53.720|E|name=Antarctia's Inner Pole of Inaccessibility}}, {{Convert|1179.4|km|abbr=on}} from the grounding lines.

The southern pole of inaccessibility is far more remote and difficult to reach than the [[geographic South Pole]]. On 14 December 1958, the [[3rd Soviet Antarctic Expedition]] for [[International Geophysical Year]] research work, led by [[Yevgeny Tolstikov]], established the temporary [[Pole of inaccessibility (Antarctic research station)|Pole of Inaccessibility Station]] ({{langx|ru|полюс недоступности}}, {{transliteration|ru|polyus nedostupnosti}}) at {{Coord|82|6|S|54|58|E|name=Pole of Inaccessibility Station}}. A second Russian team returned there in 1967. Today, a building still remains at this location, marked by a bust of [[Vladimir Lenin]] that faces towards [[Moscow]], and protected as a historical site.

On 11 December 2005, at 7:57 UTC, [[Ramón Hernando de Larramendi]], Juan Manuel Viu, and Ignacio Oficialdegui, members of the Spanish Transantarctic Expedition, reached for the first time in history the southern pole of inaccessibility at {{Coord|82|53|14|S|55|4|30|E|name=British Antarctic Survey-accredited Pole of Inaccessibility}}, updated that year by the British Antarctic Survey. The team continued their journey towards the second southern pole of inaccessibility, the one that accounts for the ice shelves as well as the continental land, and they were the first expedition to reach it, on 14 December 2005, at {{Coord|83|50|37|S|65|43|30|E|name=British Antarctic Survey-accredited Pole of Inaccessibility}}. Both achievements took place within an ambitious pioneer crossing of the eastern Antarctic Plateau that started at [[Novolazarevskaya Station]] and ended at Progress Base after more than {{convert|4,500|km|abbr=on}}. This was the fastest polar journey ever achieved without mechanical aid, with an average rate of around {{convert|90|km|abbr=on}} per day and a maximum of {{convert|311|km|abbr=on}} per day, using kites as their power source.<ref name="thepoles.com">{{Cite web |url=http://www.explorersweb.com/polar/news.php?id=1298 |title=Spaniards reach the 'second' South Pole of Inaccessibility – still no trace of Lenin |date=15 December 2005 |publisher=ExplorersWeb |website=ThePoles.com<!--sic--> |access-date=10 November 2016 |url-status=dead |archive-url=https://web.archive.org/web/20160414194423/http://www.explorersweb.com/polar/news.php?id=1298 |archive-date=14 April 2016}}</ref><ref>{{cite web |url=http://www.thepoles.com/news.php?id=1276 |title=Spaniards reach South Pole of Inaccessibility – but where is Lenin? |date=12 December 2012 |publisher=ExplorersWeb |website=ThePoles.com<!--sic-->|access-date=10 November 2016|url-status=dead|archive-url=https://web.archive.org/web/20080321061128/http://www.thepoles.com/news.php?id=1276|archive-date=21 March 2008}}</ref><ref>{{cite web|url=http://www.barrabes.com/actualidad/noticias/1-4549/alcanzado-polo-sur-inaccesibilidad.html|title=Alcanzado el Polo Sur de la Inaccesibilidad|language=es|trans-title=Reached the Southern Pole of Inaccessibility|date=13 December 2005|website=Barrabes|access-date=10 November 2016|url-status=dead|archive-url=https://web.archive.org/web/20161110173042/http://www.barrabes.com/actualidad/noticias/1-4549/alcanzado-polo-sur-inaccesibilidad.html|archive-date=10 November 2016}}</ref><ref>{{Cite web|url=http://www.tierraspolares.es/trineodeviento/ramon-h-larramendi/|title=Ramón Larramendi|website=Tierras Polares|archive-url=https://web.archive.org/web/20090111011301/http://www.tierraspolares.es/catamaran/inaccesibilidad_i.htm|archive-date=11 January 2009|url-status=dead|access-date=10 November 2016}}</ref>

On 4 December 2006, Team N2i, consisting of [[Henry Cookson]], Rupert Longsdon, Rory Sweet and [[Paul Landry]], embarked on an expedition to be the first to reach the historic pole of inaccessibility location without direct mechanical assistance, using a combination of traditional [[Manhauling|man hauling]] and [[kite skiing]]. The team reached the old abandoned station on 19 January 2007, rediscovering the forgotten statue of Lenin left there by the Soviets some 48 years previously.<ref name="teamn2i">{{cite web | url=http://www.teamn2i.com/| archive-url=https://web.archive.org/web/20110816171549/http://www.teamn2i.com/| url-status=dead| archive-date=16 August 2011| title=Team N2i successfully conquer the Pole of Inaccessibility by foot and kite on 19th Jan '07 | access-date=16 August 2011}}</ref> The team found that only the bust on top of the building remained visible; the rest was buried under the snow.<ref name="BBC" /> The explorers were picked up from the spot by a plane from [[Vostok Station|Vostok]] base, flown to [[Progress Base]] and taken back to [[Cape Town]] on the ''[[Akademik Fyodorov]]'', a Russian polar research vessel.<ref name="BBC">{{Cite web|url=http://news.bbc.co.uk/2/hi/uk_news/6281839.stm|title=UK team makes polar trek history|date=20 January 2007|website=[[BBC News]]|access-date=10 November 2016|url-status=live|archive-url=https://web.archive.org/web/20161122051626/http://news.bbc.co.uk/2/hi/uk_news/6281839.stm|archive-date=22 November 2016}}</ref>

On 27 December 2011, [[Sebastian Copeland]] and partner Eric McNair-Laundry also reached the {{Coord|82|6|S|54|58|E|name=Pole of Inaccessibility Station}} southern pole of inaccessibility. They were the first to do so without resupply or mechanical support, departing from [[Novolazarevskaya Station]] on their way to the [[South Pole]] to complete the first East/West crossing of Antarctica through both poles, over {{cvt|4,000|km}}.<ref>{{cite web|url=http://www.explorersweb.com/polar/news.php?id=20632|title=ExWeb interview Sebastian Copeland and Eric McNair-Landry (part 1/2): The battle of body and gear across 2 South Poles|date=5 March 2012|website=ExplorersWeb|access-date=10 November 2016|url-status=dead|archive-url=https://web.archive.org/web/20160529035501/http://www.explorersweb.com/polar/news.php?id=20632|archive-date=29 May 2016}}</ref>

As mentioned above, due to improvements in technology and the position of the continental edge of Antarctica being debated, the exact position of the best estimate of the pole of inaccessibility may vary. However, for the convenience of sport expeditions, a fixed point is preferred, and the Soviet station has been used for this role. This has been recognized by ''[[Guinness World Records]]'' for Team N2i's expedition in 2006–2007.<ref>{{cite web |url=http://www.teamn2i.com/media/files/guinness_book_records_team_n2i_antarctic_ec1.jpg |title=Image: guinness_book_records_team_n2i_antarctic_ec1.jpg, (539 × 791 px) |date=19 January 2007 |publisher=Team n2i |access-date=10 November 2016 |url-status=dead |archive-url=https://web.archive.org/web/20160514041543/http://www.teamn2i.com/media/files/guinness_book_records_team_n2i_antarctic_ec1.jpg |archive-date=14 May 2016 }}</ref>{{better source needed|reason=No context for [[WP:V|verification]]|date=June 2024}}

==Oceanic pole of inaccessibility==
[[File:Location of Point Nemo in the South Pacific Ocean.png|thumb|Location of Point Nemo in relation to three closest coastline points]]
The oceanic pole of inaccessibility, also known as '''Point Nemo''', is located at roughly {{Coord|48|52.6|S|123|23.6|W|format=dms}}<ref name="Where is Point Nemo">{{cite web | url=https://oceanservice.noaa.gov/facts/nemo.html |title=Where is Point Nemo? |work=[[National Oceanic and Atmospheric Administration]] |access-date=1 January 2023 }}</ref> and is the place in the ocean that is farthest from land. It represents the solution to the "longest swim" problem.<ref name="Point Nemo, revisited">{{cite web |last=Lukatela |first=Hrvoje |date=September 2022 |title=Point Nemo, revisited |url=http://www.lukatela.com/pointNemoRevisited/index.html |website=lukatela.com}}</ref> The problem entails finding such a place in the world ocean where, if a person fell overboard while on a ship at sea, they would be as far away from any land in any direction as possible. It lies in the [[South Pacific Ocean]], and is equally distant from the three closest land vertices which are each roughly {{Convert|2688|km|abbr=on}} away. Those vertices are [[Pandora Islet]] of the [[Ducie Island]] atoll (an island of the [[Pitcairn Islands]]) to the north; [[Motu Nui]] (adjacent to [[Easter Island]]) to the northeast; and [[Maher Island]] (near the larger [[Siple Island]], off the coast of [[Marie Byrd Land]], Antarctica) to the south.<ref name="Where is Point Nemo"/> The exact coordinates of Point Nemo depend on what the exact coordinates of these three islands are, since the nature of the "longest swim" problem means that the ocean point is equally far from each.<ref name="Point Nemo, revisited"/>

The three nearest land points are {{Convert|2688|km|abbr=on}} away from Point Nemo, but on a map, the three islands nearest will be listed at slightly different distances, because maps list the distance to the center of each respective island instead of each of the exact coastal points on the islands used to calculate Point Nemo. 

The area is so remote that, since no regular marine or air traffic routes are within {{convert|400|km}}, sometimes the closest human beings are astronauts aboard the [[International Space Station]] when it passes overhead.<ref name="pointnemo"/><ref name=Plastic>{{cite news |title=Point Nemo is the most remote oceanic spot – yet it's still awash with plastic |url=https://www.theguardian.com/environment/shortcuts/2018/may/18/point-nemo-is-the-most-remote-oceanic-spot-yet-its-still-awash-with-plastic |access-date=24 July 2019 |work=The Guardian |date=18 May 2018}}</ref>

The [[Antipodal point|antipode]] of Point Nemo – the point on the surface of the Earth that is diametrically opposite of it – is located at roughly {{Coord|48|52.6|N|56|36.4|E|format=dms}}, in the [[Aktobe]] region of western [[Kazakhstan]], roughly 50&nbsp;km (30 miles) SSE of the town of Shubarkuduk.

Point Nemo is relatively lifeless; its location within the [[South Pacific Gyre]] blocks nutrients from reaching the area, and being so far from land it gets little nutrient run-off from coastal waters.<ref name="pointnemo">{{cite news|url=http://www.bbc.com/earth/story/20161004-the-place-furthest-from-land-is-known-as-point-nemo |title=The Place Furthest from Land is Known as Point Nemo |last=Davies |first=Ella |date=5 October 2016 |publisher=[[BBC]]|access-date=24 July 2019 }}</ref>

To the west the region of the South Pacific Ocean is also the site of the geographic center of the [[water hemisphere]], at {{Coord|47.411667|S|177.379167|E|format=dms|type:landmark_region:FR_scale:10000|display=inline}} near [[New Zealand]]'s [[Bounty Islands]]. The geographic center of the [[Pacific Ocean]] lies further north-west where the [[Line Islands]] begin, west from [[Starbuck Island]] at {{Coord|4.97|S|158.75|W|format=dms|type:landmark_region:FR_scale:10000|display=inline}}.<ref>{{cite web |work=International Journal of Oceans and Oceanography |volume=15 |issue=1 |year=2021 |title=Determining the Areas and Geographical Centers of Pacific Ocean and its Northern and Southern Halves |pages=25–31 |first=Arjun |last=Tan |publisher=Research India Publications |url=https://www.ripublication.com/Volume/ijoov15n1.htm | ref={{sfnref}} |issn=0973-2667 | access-date=18 July 2022}}</ref>

===History===
Point Nemo was first identified by Croatian survey engineer {{ill|Hrvoje Lukatela|fr}} in 1992.<ref name=Plastic/> In 2022, Lukatela recalculated the coordinates of Point Nemo using OpenStreetMap data and Google Maps data in order to compare those results with the coordinates he first calculated using [[Digital Chart of the World]] data.<ref name="Point Nemo, revisited"/>

The point and the areas around it have attracted literary and cultural attention, and the point has become known as Point Nemo, which is Latin for "nobody" and a reference to [[Jules Verne]]'s [[Captain Nemo]] from the 1870 novel ''[[Twenty Thousand Leagues Under the Seas]]''.<ref name="pointnemo" /><ref name="Where is Point Nemo"/> The novel was a childhood favorite of Lukatela's, and such, he named the point after Captain Nemo.<ref name="Where is Point Nemo"/><ref>{{cite web | url=https://www.lukatela.com/pointnemo/ | title=Point Nemo |access-date= |website=lukatela.com|first= Hrvoje |last =Lukatela|date = 2022 }}</ref> The general area plays a major role in the 1928 short story "[[The Call of Cthulhu]]" by [[H. P. Lovecraft]], as holding the location of the fictional city of [[R'lyeh]], although this story was written 66 years before the identification of Point Nemo.<ref name="pointnemo" />

The wider area is also known as a "[[spacecraft cemetery]]", because hundreds of decommissioned satellites, space stations, and other spacecraft have been made to fall there upon re-entering the atmosphere, to lessen the risk of hitting inhabited locations<ref>{{cite magazine |last=Stirone|first=Shannon|date=13 June 2016|title=This Is Where the International Space Station Will Go to Die|url=http://www.popsci.com/this-is-where-international-space-station-will-go-to-die|magazine=[[Popular Science]]|access-date=10 November 2016|url-status=live|archive-url=https://archive.today/20160616122323/http://www.popsci.com/this-is-where-international-space-station-will-go-to-die|archive-date=16 June 2016}}</ref> or [[Sea lane|maritime traffic]]. The International Space Station (ISS) is planned to crash into Point Nemo in 2031.<ref>{{cite news|url=https://www.bbc.com/news/science-environment-60246032 |title=International Space Station to crash down to Earth in January 2031 |last=|first= |date=3 February 2022 |publisher=[[BBC News]]|access-date=3 February 2022 }}</ref><ref>{{cite web | url=https://www.nasa.gov/feature/faq-the-international-space-station-2022-transition-plan | title=FAQ: The International Space Station 2022 Transition Plan | newspaper=NASA | date=11 February 2022 | last1=Bock | first1=Michael }}</ref>

==Continental poles of inaccessibility==
===Eurasia===
{{multiple image
 | align = right
 | total_width = 500
 | image1 = Continental_pole_of_inaccessibility.png
 | caption1 = Proposed continental pole of inaccessibility at 46°17′N 86°40′E
 | image2 = Distance to the sea in Asia.jpg
 | caption2 = Distance to the sea in Asia, showing the two candidate locations for Eurasian pole of inaccessibility.
}}
The Eurasian pole of inaccessibility (EPIA) is located in northwestern [[China]], near the [[Kazakhstan]] border. It is also the furthest possible point on land from the ocean anywhere on Earth.

However, Eurasia (or even Asia alone) being the largest continent does not necessarily mean that its pole of inaccessibility is the furthest from the ocean anywhere.

Earlier calculations suggested that it is {{convert|2,645|km|mi|abbr=on}} from the nearest coastline, located at {{Coord|46|17|N|86|40|E|name=Proposed Continental Pole of Inaccessibility}}, approximately {{convert|320|km|mi|abbr=on}} north of the city of [[Ürümqi]], in the [[Xinjiang|Xinjiang Autonomous Region]] of [[China]], in the [[Gurbantünggüt Desert]]. The nearest settlements to this location are [[Hoxtolgay]] [[Town (PRC)|Town]] at {{Coord|46|34|N|85|58|E|name=Hoxtolgay}}, about {{convert|50|km|mi|abbr=on}} to the northwest, Xazgat [[Township (PRC)|Township]] ({{lang-zh|s={{ill|夏孜盖乡|zh|vertical-align=sup}}|p=Xiàzīgài xiāng}}) at {{Coord|46|20|N|86|22|E|name=Xazgat}}, about {{convert|20|km|mi|abbr=on}} to the west, and Suluk at {{Coord|46|15|N|86|50|E|name=Suluk}}, about {{convert|10|km|mi|abbr=on}} to the east.{{citation needed|date=February 2017}}

However, the previous pole location disregards the [[Gulf of Ob]] as part of the oceans, and a 2007 study<ref name="Garcia2007"/> proposes two other locations as the ones farther from any ocean (within the uncertainty of coastline definition): EPIA1 {{Coord|44.29|N|82.19|E}} and EPIA2 {{Coord|45.28|N|88.14|E}}, located respectively at 2,510±10&nbsp;km (1,560±6&nbsp;mi) and 2,514±7&nbsp;km (1,562±4&nbsp;mi) from the oceans.<ref name="Garcia2007" /> These points lie in a close triangle about the [[Dzungarian Gate]], a significant historical gateway to migration between the East and West. EPIA2 is located near a settlement called ''K̂as K̂îr Su'' in a region named ''K̂îzîlk̂um'' (قىزىلقۇم) in the {{ill|Karamgay Township|zh|喀拉玛盖乡}}, [[Burultokay County]].

Elsewhere in Xinjiang, the location {{coord|43|40|52|N|87|19|52|E}} in the southwestern suburbs of [[Ürümqi]] ([[Ürümqi County]]) was designated by local geography experts as the "center point of Asia" in 1992, and a [[Geographical Center of Asian Continent|monument to this effect]] was erected there in the 1990s. The site is a local tourist attraction.<ref name="confluence">{{cite web|url=http://www.confluence.org/confluence.php?visitid=12710|title=43° 40' 52"N 87° 19' 52" E Geographic Center of Asia&nbsp;– The Heart of Asia (亚洲之心)&nbsp;– Xinjiang (新疆), China|date=22 June 2006|website=confluence.org|publisher=Confluence|access-date=10 November 2016|url-status=live|archive-url=https://web.archive.org/web/20160602180943/http://www.confluence.org/confluence.php?visitid=12710|archive-date=2 June 2016}}</ref>

Coincidentally, the continental and oceanic poles of inaccessibility have a similar radius; the Eurasian poles EPIA1 and EPIA2 are about {{convert|178|km|abbr=on}} closer to the ocean than the oceanic pole is to land.

===Africa===
In [[Africa]], the pole of inaccessibility is at {{Coord|5.65|N|26.17|E|}}, {{convert|1814|km|mi|abbr=on}} from the coast,<ref name="Garcia2007" /> near the town of [[Obo]] in the [[Central African Republic]] and close to the country's [[tripoint]] with [[South Sudan]] and the [[Democratic Republic of the Congo]].

===North America===
[[File:North American Pole of Inaccessibility.jpg|thumb|The North-West portion of the North American Pole of Inaccessibility.]]
In [[North America]], the continental pole of inaccessibility is on the [[Pine Ridge Reservation]] in southwest [[South Dakota]] about {{convert|11|km|0|abbr=on}} north of the town of [[Allen, South Dakota|Allen]], {{convert|1650|km|mi|abbr=on}} from the nearest coastline at {{Coord|43.36|N|101.97|W|name=Pole of Inaccessibility North America}}.<ref name="Garcia2007" /> The first documented visit was in 2014 by two travelers and a local resident.<ref>{{cite web | url=http://www.penryfamily.com/surveying/poleofinaccessibility.html | title=Pole of Inaccessibility - North America }}</ref> The pole was marked in 2021 with a marker that represents the 7 Lakota Values and the four colors of the Lakota Medicine Wheel.<ref>{{Cite web |last=Henderson |first=Kyle |title=Marking the North American Pole of Inaccessibility |url=https://loving-the-world.squarespace.com/dayword/2021/7/13/north-american-pole-of-inaccessibility |date=July 13, 2021 |archive-url=https://web.archive.org/web/20210713221659/https://loving-the-world.squarespace.com/dayword/2021/7/13/north-american-pole-of-inaccessibility |archive-date=13 July 2021 |url-status=live }}</ref>

===South America===
In [[South America]], the continental pole of inaccessibility is in Brazil at {{Coord|14.05|S|56.85|W|name=Continental Pole of Inaccessibility in South America}}, near [[Arenápolis]], [[Mato Grosso]],<ref name="Garcia2007" /> {{convert|1504|km|mi|abbr=on}} from the nearest coastline. In 2017, [[the Turner Twins]] went from coastal Chile to the South American Pole of Inaccessibility, becoming the first adventurers to go from the nearest coastline to the pole by foot.<ref>{{cite web |url=https://www.countrylife.co.uk/out-and-about/interview-the-turner-twins-167649 |first=Rosie |last=Paterson |title=The Turner Twins on trekking to the Green Pole, avoiding disaster and 'fields of plastic stretching for miles' |work=[[Country Life (magazine)|Country Life]] |date=30 October 2017 |url-status=live |archive-url=https://web.archive.org/web/20180110234250/http://www.countrylife.co.uk/out-and-about/interview-the-turner-twins-167649 |archive-date=10 January 2018}}</ref> In 2019, it was discovered that there is a second South American pole of inaccessibility to the north, its position varying greatly between the two coastline datasets used.<ref name="Barnes2019"/>

===Australia===
[[File:Pole of innaccessibility.jpg|thumb|Australian Pole of Inaccessibility]]
In [[Australia (continent)|Australia]], the continental pole of inaccessibility is located at {{Coord|23.17|S|132.27|E|name=Continental Pole of Inaccessibility of Australia}}<ref name="Garcia2007" />  {{convert|920|km|mi|abbr=on}} from the nearest coastline, approximately 161&nbsp;km (100 miles) west-northwest of [[Alice Springs]]. The nearest town is [[Papunya]], [[Northern Territory]], about {{convert|30|km|abbr=on}} west-southwest of the pole.

==Methods of calculation==
As detailed below, several factors determine how a pole is calculated using computer modeling.

Poles are calculated with respect to a particular coastline dataset. Currently used datasets are the [[GSHHG]] (Global Self-consistent, Hierarchical, High-resolution Geography Database)<ref name="GSHHG"/> as well as [[OpenStreetMap]] (OSM) planet dumps. The GSHHG claims 500-meter precision for 90% of identifiable coastal features, while the volunteer-build OSM give no such guarantee but nevertheless "have characteristics suggesting accuracy".<ref name="Barnes2019"/>

Next, a [[distance function]] must be determined for calculating distances between coastlines and potential Poles. Some works tended to project data onto planes or perform spherical calculations; more recently, other works have used different algorithms and high-performance computing with [[geodesics on an ellipsoid|ellipsoidal calculations]].<ref name="Barnes2019"/>

Finally, an optimization algorithm must be developed. Several works<ref name="Garcia2007"/><ref name="Rees2014"/> use the 2007 adaptive grid method of [[Daniel Garcia-Castellanos|Garcia-Castellanos]] and Lombardo. In this method, a rectangular grid of, e.g., 21×21 points is created. Each point's distance from the coastline is determined and the point farthest from the coast identified. The grid is then recentered on this point and shrunk by some factor. This process iterates until the grid becomes very small (e.g. at 100-meter precision).<ref name="Rees2014"/> Some authors claim this method could sink into a [[local minimum]].<ref name="Rees2021"/> A more recent method from 2019, B9-Hillclimbing by Barnes, uses a polyhedron in 3D space to find initial points evenly spaced by 100 kilometers. These points are then grouped; the more "unique" points are subject to [[numerical optimization]] ([[hill climbing]], [[simulated annealing]]) for the farthest distance, accelerated by a 3D Cartesian point cloud.<ref name="Barnes2019"/> Rees (2021) shows that the two methods agree with each other to meter level.<ref name="Rees2021"/>

To date there has been no meta-study of the various works, and the algorithms and datasets they use. However, successive works have compared themselves with previous calculations and claimed improvement. For example, the GC & L article from 2007 was able to find hundred-kilometer errors in the "traditional" Eurasian PIA in Crane & Crane, 1987.<ref name="Garcia2007"/> Rees using the same method updated the arctic PIA by over 200 kilometers.<ref name="Rees2014"/> Barnes, which improved upon the method and the dataset used, was able to improve the GC & L South American PIA by 50 kilometers, showing that bad coastline data caused an error of 57 kilometers in their reported PIA-to-coast distance.<ref name="Barnes2019"/>

==List of poles of inaccessibility==
Poles of Inaccessibility, as determined by some authors, are listed in the table below. This list is incomplete and may not capture all works done to date.<!-- Try to sort by date. -->

{| class="wikitable sortable"
|+ Poles of inaccessibility as calculated by various authors
|-
! Pole
! Location
! Distance from<br />coast (km)
! Dataset
! Projection
! Method
! class="unsortable" | Reference
|-
|Africa
|{{Coord|  5.65|  26.17|dim:2000km}}
| 1,814
| GSHHS 1996
| Sphere
| Adaptive Grid
| Garcia-Castellanos (2007)<ref name="Garcia2007"/>
|-
|Africa
|{{Coord| 5.6413|  26.1533|dim:2000km}}
| 1,814.5158
| GSHHG v2.3.6 (L1)
| WGS84
| B9-Hillclimbing
| Barnes (2019)<ref name="Barnes2019"/>
|-
|Africa
|{{Coord| 5.6589|  26.1295|dim:2000km}}
|  1,815.4150
| OpenStreetMap
| WGS84
| B9-Hillclimbing
| Barnes (2019)<ref name="Barnes2019"/>
|-
|Antarctica
|{{Coord|82|06|S|54|58|E}}
|1,301
|? Traditional
|?
|?
|Soviet site (1958)<ref name="meteorological" />
|-
|Antarctica
|{{Coord| -77.3963|  105.3855|dim:2000km}}
| 1,136.2129
| GSHHG v2.3.6 (L1+L6).  Erroneous.
| WGS84
| B9-Hillclimbing
| Barnes (2019)<ref name="Barnes2019"/>
|-
|Antarctica
|{{Coord| -78.2633|  103.6340|dim:2000km}}
| 1,273.2928
| GSHHG v2.3.6 (L1+L5). Erroneous.
| WGS84
| B9-Hillclimbing
| Barnes (2019)<ref name="Barnes2019"/>
|-
|Antarctica
|{{Coord| -83.904|  64.890|dim:2000km}}
| 1,590.36
| ADDv7.2 "Outer"
| WGS84
| B9-Hillclimbing
| Rees (2021)<ref name="Rees2021"/>
|-
|Antarctica
|{{Coord| -83.610|  53.720|dim:2000km}}
| 1,179.40
| ADDv7.2 "Inner"
| WGS84
| B9-Hillclimbing
| Rees (2021)<ref name="Rees2021"/>
|-
|Arctic Pole
|{{Coord| 85.802|  176.149|dim:2000km}}
| 1,008
| GSHHG 2014
| WGS84
| Adaptive Grid
| Rees (2014)<ref name="Rees2014" />
|-
|Arctic Pole
|{{Coord| 85.7911|  176.2386|dim:2000km}}
| 1,008.9112
| OpenStreetMap
| WGS84
| B9-Hillclimbing
| Barnes (2019)<ref name="Barnes2019"/>
|-
|Arctic Pole
|{{Coord| 85.8015|  176.1423|dim:2000km}}
| 1,007.6777
| GSHHG v2.3.6 (L1)
| WGS84
| B9-Hillclimbing
| Barnes (2019)<ref name="Barnes2019"/>
|-
|Atlantic Ocean
|{{Coord| 24.1851|  -43.3704|dim:2000km}}
| 2,033.8849
| OpenStreetMap
| WGS84
| B9-Hillclimbing
| Barnes (2019)<ref name="Barnes2019"/>
|-
|Atlantic Ocean
|{{Coord| 24.1923|  -43.3728|dim:2000km}}
| 2,033.5187
| GSHHG v2.3.6 (L1)
| WGS84
| B9-Hillclimbing
| Barnes (2019)<ref name="Barnes2019"/>
|-
|Australia
|{{Coord|  -23.17|   132.27|dim:2000km}}
| 928{{NoteTag|Claimed; actually 915.6601 in GSHHG v2.3.6.<ref name="Barnes2019"/>}}
| GSHHS 1996
| Sphere
| Adaptive Grid
| Garcia-Castellanos (2007)<ref name="Garcia2007"/>
|-
|Australia
|{{Coord|23|2|S|132|10|E|dim:2000km}}
|not claimed
|SF53-13
|?
|Planar map
|Geoscience Australia (2014)<ref>{{Cite web|url=http://www.ga.gov.au/scientific-topics/national-location-information/dimensions/centre-of-australia-states-territories|title=Centre of Australia, States and Territories|website=ga.gov.au|date=15 May 2014 |publisher=[[Geoscience Australia]]|access-date=10 November 2016|url-status=live|archive-url=https://web.archive.org/web/20161031170641/http://www.ga.gov.au/scientific-topics/national-location-information/dimensions/centre-of-australia-states-territories|archive-date=31 October 2016}}</ref>
|-
|Australia
|{{Coord| -23.1732|  132.2759|dim:2000km}}
| 925.4459
| GSHHG v2.3.6 (L1)
| WGS84
| B9-Hillclimbing
| Barnes (2019)<ref name="Barnes2019"/>
|-
|Australia
|{{Coord| -23.1948|  132.1727|dim:2000km}}
| 921.9290
| OpenStreetMap
| WGS84
| B9-Hillclimbing
| Barnes (2019)<ref name="Barnes2019"/>
|-
|Eurasia 1
|{{Coord|  45.28|   88.14|dim:2000km}}
| 2,514
| GSHHS 1996
| Sphere
| Adaptive Grid
| Garcia-Castellanos (2007)<ref name="Garcia2007"/>
|-
|Eurasia 1
|{{Coord| 45.3413|  88.2483|dim:2000km}}
| 2,513.9415
| GSHHG v2.3.6 (L1)
| WGS84
| B9-Hillclimbing
| Barnes (2019)<ref name="Barnes2019"/>
|-
|Eurasia 1
|{{Coord| 45.4435|  88.3172|dim:2000km}}
| 2,509.9536
| OpenStreetMap
| WGS84
| B9-Hillclimbing
| Barnes (2019)<ref name="Barnes2019"/>
|-
|Eurasia 2
|{{Coord|  44.29|   82.19|dim:2000km}}
| 2,510
| GSHHS 1996
| Sphere
| Adaptive Grid
| Garcia-Castellanos (2007)<ref name="Garcia2007"/>
|-
|Eurasia 2
|{{Coord| 44.3184|  82.1144|dim:2000km}}
| 2,509.9685
| GSHHG v2.3.6 (L1)
| WGS84
| B9-Hillclimbing
| Barnes (2019)<ref name="Barnes2019"/>
|-
|Eurasia 2
|{{Coord| 44.6740|  83.9694|dim:2000km}}
| 2,505.2134
| OpenStreetMap
| WGS84
| B9-Hillclimbing
| Barnes (2019)<ref name="Barnes2019"/>
|-
|Great Britain
|{{Coord|  52.65|   -1.56|dim:2000km}}
| 108
| GSHHS 1996
| Sphere
| Adaptive Grid
| Garcia-Castellanos (2007)<ref name="Garcia2007"/>
|-
|Great Britain
|{{Coord| 52.0141|   -0.9640|dim:2000km}}
| 114.4462
| OpenStreetMap
| WGS84
| B9-Hillclimbing
| Barnes (2019)<ref name="Barnes2019"/>
|-
|Great Britain
|{{Coord| 52.6552|   -1.5641|dim:2000km}}
| 108.0925
| GSHHG v2.3.6 (L1)
| WGS84
| B9-Hillclimbing
| Barnes (2019)<ref name="Barnes2019"/>
|-
|Greenland
|{{Coord|  76.50|   -41.0|dim:2000km}}
| 469
| GSHHS 1996
| Sphere
| Adaptive Grid
| Garcia-Castellanos (2007)<ref name="Garcia2007"/>
|-
|Greenland
|{{Coord| 75.9660|  -40.4239|dim:2000km}}
| 471.9905
| GSHHG v2.3.6 (L1)
| WGS84
| B9-Hillclimbing
| Barnes (2019)<ref name="Barnes2019"/>
|-
|Greenland
|{{Coord| 76.0305|  -40.3902|dim:2000km}}
| 474.2257
| OpenStreetMap
| WGS84
| B9-Hillclimbing
| Barnes (2019)<ref name="Barnes2019"/>
|-
|Indian Ocean
|{{Coord| -47.6319|  99.9677|dim:2000km}}
| 1,940.8913
| OpenStreetMap
| WGS84
| B9-Hillclimbing
| Barnes (2019)<ref name="Barnes2019"/>
|-
|Indian Ocean
|{{Coord| -47.7347|  100.0547|dim:2000km}}
| 1,943.3848
| GSHHG L1
| WGS84
| B9-Hillclimbing
| Barnes (2019)<ref name="Barnes2019"/>
|-
|Madagascar
|{{Coord|  -18.33|   46.67|dim:2000km}}
| 260
| GSHHS 1996
| Sphere
| Adaptive Grid
| Garcia-Castellanos (2007)<ref name="Garcia2007"/>
|-
|Madagascar
|{{Coord|  -18.3382|     46.6663|dim:2000km}}
| 259.5957
| GSHHG v2.3.6 (L1)
| WGS84
| B9-Hillclimbing
| Barnes (2019)<ref name="Barnes2019"/>
|-
|Madagascar
|{{Coord| -18.2645|     46.7003|dim:2000km}}
| 264.0657
| OpenStreetMap
| WGS84
| B9-Hillclimbing
| Barnes (2019)<ref name="Barnes2019"/>
|-
|North America
|{{Coord|  43.46|   -101.97|dim:2000km}}
| 1,639{{NoteTag|Claimed; actually 1629.7740 in GSHHG v2.3.6.<ref name="Barnes2019"/>}}
| GSHHS 1996
| Sphere
| Adaptive Grid
| Garcia-Castellanos (2007)<ref name="Garcia2007"/>
|-
|North America
|{{Coord| 43.3764|  -102.0111|dim:2000km}}
| 1,639.6549
| GSHHG v2.3.6 (L1)
| WGS84
| B9-Hillclimbing
| Barnes (2019)<ref name="Barnes2019"/>
|-
|North America
|{{Coord| 43.4370|  -102.0101|dim:2000km}}
| 1,643.7562
| OpenStreetMap
| WGS84
| B9-Hillclimbing
| Barnes (2019)<ref name="Barnes2019"/>
|-
|Pacific Ocean (Point Nemo)
|{{Coord|  -48.89|   -123.45|dim:2000km}}
| 2,690
| GSHHS 1996
| Sphere
| Adaptive Grid
| Garcia-Castellanos (2007)<ref name="Garcia2007"/>
|-
|Pacific Ocean (Point Nemo)
|{{Coord| -49.0031|   -123.3920|dim:2000km}}
| 2,701.1721
| OpenStreetMap
| WGS84
| B9-Hillclimbing
| Barnes (2019)<ref name="Barnes2019"/>
|-
|Pacific Ocean (Point Nemo)
|{{Coord| -49.0273|   -123.4345|dim:2000km}}
| 2,704.7991
| GSHHG v2.3.6 (L1)
| WGS84
| B9-Hillclimbing
| Barnes (2019)<ref name="Barnes2019"/>
|-
|South America
|{{Coord|  -14.05|   -56.85|dim:2000km}}
| 1,517{{NoteTag|Claimed; actually 1449.9471 in GSHHG v2.3.6.<ref name="Barnes2019"/>}}
| GSHHS 1996
| Sphere
| Adaptive Grid
| Garcia-Castellanos (2007)<ref name="Garcia2007"/>
|-
|South America 1
|{{Coord| -14.3902|  -56.9922|dim:2000km}}
| 1,490.5321
| GSHHG v2.3.6 (L1)
| WGS84
| B9-Hillclimbing
| Barnes (2019)<ref name="Barnes2019"/>
|-
|South America 1
|{{Coord| -6.3248|  -63.1885|dim:2000km}}
| 1,511.6636
| OpenStreetMap
| WGS84
| B9-Hillclimbing
| Barnes (2019)<ref name="Barnes2019"/>
|-
|South America 2
|{{Coord| -10.7342|  -59.2126|dim:2000km}}
|  1,467.2206
| OpenStreetMap
| WGS84
| B9-Hillclimbing
| Barnes (2019)<ref name="Barnes2019"/>
|-
|South America 2
|{{Coord| -5.0537|  -65.5487|dim:2000km}}
| 1,476.4901
| GSHHG v2.3.6 (L1)
| WGS84
| B9-Hillclimbing
| Barnes (2019)<ref name="Barnes2019"/>
|}
{{NoteFoot}}

ArcGIS personnel wrote a 2015 page with their calculations based on a flat Earth. The results are too inaccurate to be included here.<ref name="Barnes2019"/>

==See also==
* [[Antipodes]]
* [[Extremes on Earth]]
* [[Geographical pole]]
* [[Geographical centre]]
* [[Land and water hemispheres]]
* [[List of mainland settlements that are inaccessible by road]]
* [[Pole of Inaccessibility research station]]

==References==
{{Reflist|30em|refs=
<ref name="Rees2021">{{cite journal |last1=Rees |first1=Gareth |last2=Gerrish |first2=Laura |last3=Fox |first3=Adrian |last4=Barnes |first4=Richard |date=2021 |title=Finding Antarctica's Pole of Inaccessibility |doi=10.1017/S0032247421000620 |periodical=Polar Record |volume=57 |issue=e40 |pages=1–6 |s2cid=239011407 |doi-access=free |bibcode=2021PoRec..57E..40R |url=https://nora.nerc.ac.uk/id/eprint/531111/1/finding-antarcticas-pole-of-inaccessibility.pdf }}</ref>
<ref name="Barnes2019">{{cite journal |last=Barnes |first=Richard |date=2019 |title=Optimal orientations of discrete global grids and the Poles of Inaccessibility |doi=10.1080/17538947.2019.1576786 |doi-access=free |journal=[[International Journal of Digital Earth]] |volume=13 |issue=7 |pages=803–816 |s2cid=134622203 |s2cid-access=free}}</ref>
<ref name="Garcia2007">{{cite journal |last1=Garcia-Castellanos |first1=Daniel |last2=Lombardo |first2=Umberto |title=Poles of inaccessibility: A calculation algorithm for the remotest places on earth |doi=10.1080/14702540801897809 |periodical=Scottish Geographical Journal |access-date=10 November 2016 |archive-url=https://web.archive.org/web/20140629230429/http://cuba.ija.csic.es/~danielgc/papers/Garcia-Castellanos,%20Lombardo,%202007,%20SGJ.pdf|archive-date=29 June 2014|url-status=dead|date=September 2007 |volume=123 |issue=3 |pages=227–233 |bibcode=2007ScGJ..123..227G |s2cid=55876083 |url=http://cuba.ija.csic.es/~danielgc/papers/Garcia-Castellanos,%20Lombardo,%202007,%20SGJ.pdf }}</ref>
<ref name="Rees2014">{{cite journal |last1=Rees |first1=Gareth |last2=Headland |first2=Robert |last3=Scambos |first3=Ted |last4=Haran |first4=Terry |date=2014 |title=Finding the Arctic pole of inaccessibility |doi=10.1017/S003224741300051X |periodical=Polar Record|volume=50 |issue=1 |pages=86–91 |bibcode=2014PoRec..50...86R |s2cid=140637055 }}</ref>
<ref name="GSHHG">{{cite web |last1=Wessel |first1=Paul |last2=Walter |first2=Smith |year=2016 |title=A Global Self-consistent, Hierarchical, High-resolution Geography Database |url=http://www.soest.hawaii.edu/wessel/gshhg/}}</ref>
}}

==External links==
{{Commons category}}
{{GeoGroup}}
* [https://sites.google.com/site/polesofinaccessibility/ How to calculate PIAs]
* [https://web.archive.org/web/20090303234631/http://www.teamn2i.com/ Team N2i successfully conquer the Pole of Inaccessibility by foot and kite on 19th Jan '07]

{{Polar exploration|state=collapsed}}
{{Authority control}}

{{DEFAULTSORT:Pole Of Inaccessibility}}
[[Category:Extreme points of Earth]]
[[Category:Geography of Antarctica]]
[[Category:Geography of the Arctic]]
[[Category:Lists of coordinates]]
[[Category:Polar regions of the Earth]]