View source for Geography of Guam

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{{Infobox islands
| name             = [[Guam]]
| image_name       = File:Guam space image (cropped).jpg
| image_caption    = A satellite image of Guam
| image_size       =
| map_image = Bathymetric map of Guam.jpg
| map_image_caption =  Bathymetric map of the vicinity of Guam, including the Mariana Trench and East Mariana Ridge
| native_name      = Guåhan
| native_name_link = Chamorro language
| nickname         =
| location         = [[Pacific Ocean]]
|pushpin_map            = #Pacific Ocean#World
| pushpin_label_position  = 
| pushpin_map_caption     = 
| coordinates      = {{coord|13|26|31|N|144|46|35|E|display=inline,title}}
| archipelago      = [[Mariana Islands]]
| total_islands    =
| major_islands    =
| area_km2         = 544
| length_km        = 51
| width_km         = 15
| coastline_km                      = 125.5
| highest_mount    = [[Mount Lamlam]]
| elevation_m      = 406
| country          = [[United States]]
| country_admin_divisions_title     = Territory
| country_admin_divisions           = [[Guam]]
| country_admin_divisions_title_1   =
| country_admin_divisions_1         =
| country_admin_divisions_title_2   =
| country_admin_divisions_2         =
| country_capital_city              =
| country_largest_city              = [[Dededo, Guam|Dededo]]
| country_largest_city_population   = 46,000
| country_leader_title              =
| country_leader_name               =
| population       = 167,358 <ref>[https://www.cia.gov/the-world-factbook/countries/guam/ The World Factbook: Guam] {{Webarchive|url=https://web.archive.org/web/20210126164717/https://www.cia.gov/the-world-factbook/countries/guam |date=2021-01-26 }} CIA. Retrieved on October 18, 2017.</ref>
| population_as_of = July 2017 est.
| density_km2      = 320.44
| ethnic_groups    = Native [[Chamorros]] (57%), [[Filipino people|Filipino]] (25.5%), [[Race (U.S. Census)|White]] (10%), [[Overseas Chinese|Chinese]], [[Japanese people|Japanese]] and [[Korean people|Korean]] ancestry
| additional_info  =
}}
[[Guam]] is a [[Territories of the United States|U.S. territory]] in the western [[Pacific Ocean]], at the boundary of the [[Philippine Sea]]. It is the southernmost and largest member of the [[Mariana Islands]] archipelago, which is itself the northernmost group of islands in [[Micronesia]]. The closest political entity is the Commonwealth of the [[Northern Mariana Islands]] (CNMI), another U.S. territory. Guam shares [[maritime boundary|maritime boundaries]] with CNMI to the north and the [[Federated States of Micronesia]] to the south. It is located approximately one quarter of the way from the [[Philippines]] to [[Hawaii]]. Its location and size make it strategically important.  It is the only island with both [[Apra Harbor|a protected harbor]] and land for multiple airports between [[Asia]] and Hawaii, on an east–west axis, and between [[Papua New Guinea]] and [[Japan]], on a north–south axis.<ref name="Guampedia_strategic">{{cite web |last1=Rogers |first1=Robert F. |title=Guam's Strategic Value |url=https://www.guampedia.com/guams-strategic-value/ |website=Guampedia |access-date=March 14, 2021 |date=October 8, 2020 |archive-date=March 10, 2021 |archive-url=https://web.archive.org/web/20210310010444/https://www.guampedia.com/guams-strategic-value/ |url-status=live }}</ref>

The island is a [[Volcanic island|result of the volcanic activity]] created by subduction of the [[Pacific Plate]] under the [[Philippine Sea Plate]] at the nearby [[Mariana Trench]], which runs from the east of Guam to the southwest. Volcanic eruptions established the base of the island in the [[Eocene]], roughly 56 to 33.9 [[Myr|million years ago]] (mya). The north of Guam is a result of this base being covered with layers of [[coral reef]], turning into [[limestone]], and then being thrust by tectonic activity to create a plateau. The rugged south of the island is a result of more recent volcanic activity. [[Cocos Island (Guam)|Cocos Island]] off the southern tip of Guam is the largest of the many small [[islet]]s along the coastline.

Politically, Guam is divided into [[villages of Guam|19 villages]]. The majority of the population lives on the coralline limestone plateaus of the north, with political and economic activity centered in the central and northern regions. The rugged geography of the south largely limits settlement to rural coastal areas. The western coast is [[Windward and leeward|leeward]] of the [[trade winds]] and is the location of [[Apra Harbor]], the capitol [[Hagåtña, Guam|Hagåtña]], and the tourist center of [[Tumon]]. The [[United States Department of Defense|U.S. Defense Department]] owns about 29% of the island,<ref name="VOA_20170809">{{cite web |title=Guam: Small But Important Piece of US Territory in Pacific |url=https://www.voanews.com/east-asia-pacific/guam-small-important-piece-us-territory-pacific |website=VOA News |access-date=14 March 2021 |language=en |date=August 9, 2017 |archive-date=10 March 2021 |archive-url=https://web.archive.org/web/20210310070638/https://www.voanews.com/east-asia-pacific/guam-small-important-piece-us-territory-pacific |url-status=dead }}</ref> under the management of [[Joint Region Marianas]].

== Geology ==
{{main|Geology of Guam}}
{{further|List of rivers of Guam|List of beaches in Guam}}

The [[Mariana Islands]] lie atop the largely submerged East Mariana Ridge, a part of the [[Izu–Bonin–Mariana Arc|Izu–Bonin–Mariana (IBM) Arc]]. The IBM Arc is a [[plate tectonics|tectonic plate]] [[convergent boundary]] where the west [[Pacific Plate]] subducts the [[Philippine Sea Plate]]. Guam is actually located on the [[Mariana Plate]], a micro plate between the two. The subduction area is marked by the [[Mariana Trench]], the deepest gash in the earth's surface, which includes three deep spots to the south of Guam. From east to west, these are: Nero Deep, which was the deepest known spot in the ocean from 1899 to 1927 at {{Convert|9660|m|ft|abbr=on}}; [[Sirena Deep]], the third deepest measured point at {{Convert|10714|m|ft|abbr=on}}; and [[Challenger Deep]], the deepest point at {{convert|10902|to|10929|m|ft|0|abbr=on}}.

There have been three major eruptions on Guam. the first, the Facpi formation, in the mid [[Eocene]], laid the base of the island and is still the topmost formation along the southwestern coast. The second eruption created the Alutom formation that is still the topmost strata in the middle of the island. The [[Mount Alifan]]-[[Mount Lamlam]] ridge is the remnant of the Alutom formation [[caldera]].<ref name="EIS_Ch 3">{{cite web |title=Guam and CNMI Military Relocation - Final EIS - Chapter 3: Geological and Soil Resources |url=http://www.guambuildupeis.us/documents/final/volume_2/Vol_02_Ch03_Geological_and_Soil_Resources.pdf |website=Guam Buildup Environmental Impact Statement |access-date=14 March 2021 |date=July 2010 |archive-date=25 January 2012 |archive-url=https://web.archive.org/web/20120125063320/http://www.guambuildupeis.us/documents/final/volume_2/Vol_02_Ch03_Geological_and_Soil_Resources.pdf |url-status=live }}</ref>{{rp|7}}

The last volcanic layer, called the Umatac formation, was formed by the third and final eruption, which surrounded this ridge in the south of Guam. Meanwhile, volcanic activity alternately submerged areas of the island, which hosted [[coral reef]]s, and then lifted those reefs, which became [[limestone]]. The island may be divided into four general geophysical regions:{{r|"EIS_Ch 3"|p=4}} the uplifted and relatively flat [[coral]]line [[limestone]] plateau in the north that provides most of the drinking water; the low-rising hills of the Alutom Formation in the center; the mountains of the Umatac formation in the south; and the coastal lowlands ringing most of the island.{{r|"EIS_Ch 3"|p=1}} Much of the coast is protected by a [[fringing reef]].

Soils are mostly silty clay or clay and may be gray, black, brown or reddish brown; acidity and depth vary.<ref>{{cite web |url=https://casoilresource.lawr.ucdavis.edu/gmap/ |title=SoilWeb: An Online Soil Survey Browser &#124; California Soil Resource Lab |publisher=Casoilresource.lawr.ucdavis.edu |date= |access-date=2021-11-24 |archive-date=2021-11-19 |archive-url=https://web.archive.org/web/20211119221418/https://casoilresource.lawr.ucdavis.edu/gmap/ |url-status=live }}</ref> There are four [[List of National Natural Landmarks in Guam|National Natural Landmarks in Guam]] chosen as exemplars of the island's geology: [[Facpi Point]], [[Fouha Point]], [[Mount Lamlam]], and [[Two Lovers Point]].

<gallery>
File:Two lovers point (80103943).jpg|[[Two Lovers Point]], a [[List of National Natural Landmarks in Guam|National Natural Landmark]], is a sea cliff of coralline limestone in northern Guam
</gallery>

=== Earthquakes ===
{{main|List of earthquakes in Guam}}
Guam occasionally experiences earthquakes;<ref>{{cite web|last1=Mueller|first1=Charles S.|display-authors=etal|title=Seismic Hazard Assessment for Guam and the Northern Mariana Islands|url=https://pubs.usgs.gov/of/2012/1015/report/OF12-1015.pdf|publisher=U. S. Geological Survey|access-date=September 23, 2018|archive-url=https://web.archive.org/web/20180923162947/https://pubs.usgs.gov/of/2012/1015/report/OF12-1015.pdf|archive-date=September 23, 2018|url-status=live}}</ref> most with epicenters near Guam have had magnitudes ranging from 5.0 to 8.7. Unlike [[Anatahan]] in the [[Northern Mariana Islands]], Guam is not volcanically active, though [[vog|vog (volcanic smog)]] from Anatahan affects it due to proximity.<ref name="USGS Anahatan Volcano">"Home page of the Anahatan volcano". ''USGS-CNMI'', November 8, 2007. Retrieved November 8, 2007 from {{cite web|url=http://hvo.wr.usgs.gov/cnmi/|title=Home page of Anatahan Volcano, Commonwealth of the Northern Mariana Islands|access-date=November 8, 2007|url-status=dead|archive-url=https://web.archive.org/web/20071013221850/http://hvo.wr.usgs.gov/cnmi/|archive-date=October 13, 2007}}</ref>

== Strategic position ==
{{Further|History of Guam}}
Guam is about {{convert|1500|mile|km}} from both [[Tokyo]] in the north and [[Manila]] in the west, and about {{convert|3800|mile|km}} from [[Honolulu]] in the east.<ref name="Guampedia_Geography">{{cite web |last1=Karolle |first1=Bruce G. |title=Geography of Guam |url=https://www.guampedia.com/geography-of-guam/ |website=Guampedia |access-date=14 March 2021 |date=February 12, 2020 |archive-date=28 February 2021 |archive-url=https://web.archive.org/web/20210228220243/https://www.guampedia.com/geography-of-guam/ |url-status=live }}</ref> Guam's size and possession of a natural safe anchorage at [[Apra Harbor]], uniquely among its neighbors, have driven much of its history.<ref name="Guampedia_strategic"/>

Guam was a minor but integral part of the Spanish [[Manila galleon]] trade. Located on the east-to-west [[trade winds]], galleons from [[Mexico]] would briefly reprovision on Guam before continuing on to [[Manila]]. The [[westerlies]] are well away from Guam so it was not a stop on the return trip. During the height of Pacific [[whaling]], Apra Harbor was a major stop for whalers.<ref name="Guampedia_Sumay"/>

After the American [[capture of Guam]] in 1898, the [[Commercial Pacific Cable Company]] laid [[submarine communications cable]] for [[telegraph]] through [[Guam Cable Station]], linking the United States to Asia for the first time.<ref name="Guampedia_Sumay">{{cite web |last1=Babauta |first1=Leo |title=Sumay |url=https://www.guampedia.com/sumay-2/ |website=Guampedia |access-date=March 2, 2021 |date=October 14, 2019 |archive-date=March 3, 2021 |archive-url=https://web.archive.org/web/20210303144457/https://www.guampedia.com/sumay-2/ |url-status=live }}</ref> Guam continues to be [[Communications in Guam#Submarine cables|a major submarine cable hub]] in the western Pacific. In 1935, [[Pan Am|Pan American Airways]] made [[Sumay, Guam]], a base for its ''[[China Clipper]]'', the first trans-Pacific air cargo service, flying from [[San Francisco]] to [[Manila]], arrived at Sumay on November 27, 1935, and the first passenger service flight on October 21, 1936.<ref name="Guampedia_Pan Am">{{cite web |last1=Clement |first1=Michael R. Jr. |title=First Pan American Flights |url=https://www.guampedia.com/first-pan-american-flights/ |website=Guampedia |access-date=March 5, 2021 |date=October 15, 2019 |archive-date=March 4, 2021 |archive-url=https://web.archive.org/web/20210304084228/https://www.guampedia.com/first-pan-american-flights/ |url-status=live }}</ref>

The [[Battle of Guam (1941)|Japanese capture of Guam]] in 1941 and subsequent [[Battle of Guam (1944)|American liberation]] in 1944 were driven by a recognition of Guam's strategic location in a Pacific War. Military facilities on Guam, including [[Naval Base Guam]] and [[Andersen Air Force Base]], are considered critical forward deployment bases in the Asia-Pacific. Guam was a support center for the [[Korean War]] (1949–1953) and became even more important during the [[Vietnam War]], when the bombing campaigns [[Operation Arc Light]] (1965–1973) and [[Operation Linebacker II]] (1972) were flown out of Andersen Air Force Base. Guam was similarly the site of [[Operation New Life]], the processing of [[Indochina refugee crisis|Vietnamese refugee]]s after the [[Fall of Saigon]] in 1975.<ref name="Guampedia_strategic"/>

Guam is a linchpin of the "Second Island Chain" in the [[Island Chain Strategy]] first described by the U.S. during the Korean War, but which has become an increasing focus of [[Foreign policy of China|Chinese foreign policy]]. In 2016, China deployed the [[DF-26]], their first [[intermediate-range ballistic missile]] with the range to hit Guam. Chinese media wonks and military experts dubbed it the "Guam Killer."<ref>{{cite web |last1=Pappalardo |first1=Joe |title=China's "Guam Killer" Is Forcing B-2s To Practice Strikes From Pearl Harbor |url=https://www.popularmechanics.com/military/aviation/a23692731/b-2-pearl-harbor-guam-killer/ |website=Popular Mechanics |access-date=18 March 2021 |date=9 October 2018 |archive-date=17 January 2021 |archive-url=https://web.archive.org/web/20210117073808/https://www.popularmechanics.com/military/aviation/a23692731/b-2-pearl-harbor-guam-killer/ |url-status=live }}</ref>

<gallery>
File:Andersen AFB with 150 B-52s 1972.jpg|About 150 [[Boeing B-52 Stratofortress|B-52 bombers]] at [[Andersen Air Force Base]] during the [[Operation Linebacker II|1972 bombings of North Vietnam]].
File:Geographic Boundaries of the First and Second Island Chains.png|The first and [[second island chain]]s.
</gallery>

== Settlement patterns ==
{{further|Villages of Guam|List of census-designated places in Guam}}
[[File:Guam Population Density, 2000 (6171909873) (cropped).jpg|thumb|upright|A population density map of Guam, 2000]]
A 1668 description reported that there were approximately 180 [[Chamorro people|Chamoru]] villages on Guam with a total island population between 35,000 and 50,000.<ref name=NPS1>{{cite web |title=War in the Pacific National Historic Park: An Administrative History - Chapter 1: Before European Contact |url=https://www.nps.gov/parkhistory/online_books/wapa/adhi/adhi1.htm |website=National Park Service |access-date=22 June 2020 |date=8 May 2005 |archive-date=22 June 2020 |archive-url=https://web.archive.org/web/20200622000338/https://www.nps.gov/parkhistory/online_books/wapa/adhi/adhi1.htm |url-status=live }}</ref> The Spanish strategy of [[villagization]], called ''reducción'', which began in the [[Spanish-Chamorro Wars]], transferred the population to seven towns. These relocated people were forced to travel to work on distant farms and ranches, creating the ''lanchu'' system of farmsteading, which was to become a traditional part of Chamoru society well into the twentieth century.<ref name="Hezel">{{cite book |last1=Hezel |first1=Francis X. |title=When cultures clash: revisiting the 'Spanish-Chamorro Wars' |date=2015 |publisher=Richard F. Taitano Micronesian Area Research Center, University of Guam |isbn=978-1-935198-04-8 |url=https://www.academia.edu/23563686 |access-date=19 June 2020}}</ref>{{rp|48}}

A map from the early 1700s shows nearly 40 villages on Guam, mostly along the coastlines. The Spanish eventually emptied all of the northern and central villages of Guam, except for [[Hagåtña, Guam|Hagåtña]]. The population of Guam and the entire Northern Marianas, except for [[Rota (island)|Rota]], was moved to Hagåtña, and five southern villages: [[Agat, Guam|Agat]], [[Inarajan, Guam|Inarajan]], [[Merizo, Guam|Merizo]], [[Pago, Guam|Pago]] (which no longer exists), and [[Umatac, Guam|Umatac]].<ref name="Guampedia_villages">{{cite web |title=Guam Villages |url=https://www.guampedia.com/villages-heritage-sites-and-island-life/guams-villages/ |website=Guampedia |access-date=18 March 2021 |date=September 15, 2020 |archive-date=3 March 2021 |archive-url=https://web.archive.org/web/20210303150300/https://www.guampedia.com/villages-heritage-sites-and-island-life/guams-villages/ |url-status=live }}</ref> Meanwhile, outbreaks of [[infectious disease]] inflicted a terrible toll, which was accelerated by concentrating the population. The Chamoru population in 1689 was estimated at 10,000, a third to fifth of the number just 20 years previously.{{r|Hezel|p=70}}

The population changed little over the next two centuries. The population in 1901, after the American [[Capture of Guam]], was 9,676, with the majority located in Hagåtña and [[Sumay, Guam|Sumay]] on Apra Harbor. The population was 18,509 in 1930. The American Naval government build roads and schools in outlying areas in order to urge the population to spend time on their ranch lands and produce more agricultural products. There were eight municipalities approved by the Naval governor in the 1920s, Hagåtña, Agat, [[Asan, Guam|Asan]], Inarajan, Merizo, [[Piti, Guam|Piti]], Sumay and [[Yona, Guam|Yona]]. This increased to 15 in 1939.<ref name="Guampedia_resettlement">{{cite web |title=Resettlement Patterns Under American Rule |url=https://www.guampedia.com/resettlement-patterns-under-american-rule/ |website=Guampedia |publisher=Micronesian Archaeological Research Services |access-date=March 18, 2021 |date=October 15, 2019 |archive-date=April 24, 2021 |archive-url=https://web.archive.org/web/20210424090550/https://www.guampedia.com/resettlement-patterns-under-american-rule/ |url-status=live }}</ref>

The devastation from the [[Battle of Guam (1941)|U.S. retaking of Guam]] in 1944 and subsequent military build-up of installations at the end of the [[Pacific War]] transformed the island's settlements. Two municipalities that disappeared entirely after the land became military bases were Machanao in the north and Sumay on Apra Harbor, which are now part of [[Naval Base Guam]]. The military government prohibited resettlement and rebuilding of Hagåtña, which held almost half of the pre-war population. The former residents of Hagåtña dispersed, mainly to their ''lanchus'' (ranches).<ref name="Guampedia_resettlement"/>

Once most of the wartime bases were built, northern Guam experienced sustained housing construction. The original location of [[Dededo, Guam|Dededo]] was bulldozed by the Americans to create [[Harmon Air Force Base]]. When the new location was devastated by [[Typhoon Karen]] in 1962 and [[Typhoon Olive (1963)|Typhoon Olive]] in 1963, the resulting federal aid sparked a construction boom that then resulted in the first large housing subdivisions.<ref>{{cite web |title=Dededo (Dededu) |url=https://www.guampedia.com/dededo-dedidu/ |website=Guampedia |access-date=18 March 2021 |date=January 10, 2021 |archive-date=22 January 2021 |archive-url=https://web.archive.org/web/20210122215009/https://www.guampedia.com/dededo-dedidu/ |url-status=live }}</ref>

The neighboring municipality of [[Yigo, Guam|Yigo]] on the northeast of the island has experienced dramatic population growth. In 1940, there were about 40 families living in the area. By the beginning of the 21st century, it was Guam's second most populous village after Dededo.<ref name="GP_Yigo">{{cite web |last1=Clement |first1=Michael R. Jr. |title=Yigo (Yigu) |url=https://www.guampedia.com/yigo/ |website=Guampedia |access-date=March 18, 2021 |date=January 10, 2021 |archive-date=April 14, 2021 |archive-url=https://web.archive.org/web/20210414145558/https://www.guampedia.com/yigo/ |url-status=live }}</ref>

== Climate ==
[[File:A palm-lined jungle coastline on Guam (line378676781).jpg|thumb|A jungle beach coastline on Guam]]
{{main|Guam#Climate}}
{{further|Climate change in Guam|List of typhoons on Guam }}
Guam has a [[tropical marine climate]] that is generally warm and humid, but moderated by northeast [[trade winds]].  The [[dry season]] is from January to June. The [[wet season]] is from July to December. There is little temperature variation. There are frequent squalls during the wet season.  [[Typhoon]]s are relatively rare but are most common during the wet season and are potentially very destructive.

[[Typhoon Pongsona]] in 2002 had wind gusts up to 290&nbsp;km/h (183&nbsp;mph <small>1-min</small>) over Guam and caused widespread devastation, but no direct deaths because of strict building standards. Pongsona was the most damaging typhoon on Guam since [[Typhoon Paka]] in 1997.

== Environment ==
[[File:Guam2021OSM.png|thumb|An enlargeable, detailed map of Guam]]
{{main|Marianas tropical dry forests}}
{{further|Invasive species in Guam|List of birds of Guam|List of mammals of Guam|List of Superfund sites in Guam}}
The rapid proliferation of the [[brown tree snake]] (''Boiga irregularis''), an [[Introduced species|exotic species]], caused the [[local extinction]] of the native [[bird]] population, such as the [[Guam rail]] and [[Guam kingfisher]]. The island also supports feral populations of introduced [[Philippine deer]] (''Rusa marianna''), [[Wild boar#Feral pigs|pigs]] (''Sus scrofa''), and [[carabao]] (''Bubalus bubalis carabanesis'').

Extraction of natural resources for economic gain is based around the sea. This includes [[commercial fishing]], mostly servicing and unloading of [[Longline fishing|longline]] fleets and commercial vessels. There is [[recreational fishing]] of Indo-Pacific blue marlin (''[[Makaira]] [[Makaira mazara|mazara]]''), [[wahoo]] (''Acanthocybium solandri''), [[mahi-mahi]] (''Coryphaena hippurus''), [[yellowfin tuna]] (''Thunnus albacares''), and deepwater reef fish. Tourism from [[Japan]] in particular, but increasingly from [[China]] and [[South Korea]], largely derives from an attractive tropical climate and amenities.

A 2012 estimate was that 16.67% of the land area was being used for permanent crops, while only 1.85% was considered [[arable land]] suitable for plowing, planting, and reaping. 2&nbsp;km<sup>2</sup> was irrigated.

== Extreme points ==
[[File:Apra Harbor.jpg|thumb|The entrance to [[Apra Harbor]], with [[Point Udall (Guam)|Point Udall]], the westernmost point, on the right]]
The three highest points on Guam are [[Mount Lamlam]] at {{convert|406|m|ft|sp=us}}, [[Mount Jumullong Manglo]] at {{convert|391|m|ft|sp=us}}, and [[Mount Bolanos]], {{convert|368|m|ft|sp=us}}. Mount Lamlam is sometimes claimed to be the [[List of highest mountains on Earth|world's highest mountain]] at {{convert|37820|feet|m}}, measured from a base in [[Challenger Deep]] {{convert|304|km|mi|abbr=on}} away.<ref>{{cite web |last1=McMahon |first1=Mary |title=How do Scientists Determine the World's Tallest Mountain? |url=https://www.infobloom.com/how-do-scientists-determine-the-worlds-tallest-mountain.htm |website=Info Bloom |access-date=March 13, 2021 |date=January 23, 2021 |archive-date=May 20, 2021 |archive-url=https://web.archive.org/web/20210520184712/https://www.infobloom.com/how-do-scientists-determine-the-worlds-tallest-mountain.htm |url-status=live }}</ref><ref>{{cite web |last1=Fichtl |first1=Marcus |title=Guam's Mount Lamlam technically world's tallest mountain, though most of it is underwater |url=https://www.stripes.com/lifestyle/guam-s-mount-lamlam-technically-world-s-tallest-mountain-though-most-of-it-is-underwater-1.485437 |website=Stars and Stripes |access-date=March 13, 2021 |date=August 31, 2017 |archive-date=November 18, 2020 |archive-url=https://web.archive.org/web/20201118105200/https://www.stripes.com/lifestyle/guam-s-mount-lamlam-technically-world-s-tallest-mountain-though-most-of-it-is-underwater-1.485437 |url-status=live }}</ref> Even if measured from [[Sirena Deep]], {{convert|145|km|mi|sp=us}} away, Mount Lamlam is taller than [[Mauna Kea]], which is typically cited as the tallest mountain including subsurface rise from the ocean floor at {{Convert|10203|m|ft|0|abbr=on}}.

The extreme north, east, south, and west locations on mainland Guam are [[Ritidian Point]], [[Pati Point]], [[Aga Point]], and [[Point Udall (Guam)|Point Udall]], respectively. However, [[Cocos Island (Guam)|Cocos Island]], located off the southern coast of Guam's mainland is the ultimate southernmost point of the territory. Point Udall, previously named Orote Point, is also the [[List of extreme points of the United States#Interpretation of easternmost and westernmost|westernpoint point of the U.S.]], as measured from the [[geographic center of the United States]].<ref>{{cite web |title=The Most Extreme Points of the United States |url=https://www.worldatlas.com/articles/the-most-extreme-points-of-the-united-states.html |website=WorldAtlas |access-date=March 13, 2021 |date=May 28, 2018 |archive-date=February 25, 2021 |archive-url=https://web.archive.org/web/20210225054940/https://www.worldatlas.com/articles/the-most-extreme-points-of-the-united-states.html |url-status=live }}</ref><ref>{{cite web |title=Congressional Record - Proceedings and Debates of the 106th Congress, First Session - House of Representatives (Vol. 145, No. 34) |url=https://www.govinfo.gov/content/pkg/CREC-1999-03-04/pdf/CREC-1999-03-04-house.pdf |website=govinfo.gov |access-date=March 13, 2021 |page=H982 |date=March 4, 1999 |archive-date=2021-05-08 |archive-url=https://web.archive.org/web/20210508113549/https://www.govinfo.gov/content/pkg/CREC-1999-03-04/pdf/CREC-1999-03-04-house.pdf |url-status=live }}</ref>

==References ==
{{commons category}}
{{Reflist}}

{{Guam}}
{{U.S. political divisions geographies}}
{{Geography of Oceania}}

{{DEFAULTSORT:Geography Of Guam}}
[[Category:Geography of Guam| ]]