Editing Mariana Trench

{{Short description|Deepest oceanic trench on Earth}}
{{Redirect|Marianas Trench|the Canadian band|Marianas Trench (band)}}
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[[File:Marianatrenchmap.png|right|upright=1.3|thumb|Location of the Mariana Trench]]

The '''Mariana Trench''' is an [[oceanic trench]] located in the western [[Pacific Ocean]], about {{convert|200|km|mi|0}} east of the [[Mariana Islands]]; it is the [[deep sea|deepest]] oceanic trench on Earth. It is crescent-shaped and measures about {{cvt|2550|km|mi}} in length and {{cvt|69|km|mi}} in width. The maximum known depth is {{convert|10984|±|25|m|ft fathom mi}} at the southern end of a small slot-shaped valley in its floor known as the [[Challenger Deep]].<ref name="So, How Deep Is the Mariana Trench?">{{cite journal | last1=Gardner | first1=James V. | last2=Armstrong | first2=Andrew A. | last3=Calder | first3=Brian R. | last4=Beaudoin | first4=Jonathan | title=So, How Deep Is the Mariana Trench? | journal=Marine Geodesy | publisher=Informa UK Limited | volume=37 | issue=1 | date=2014-01-02 | issn=0149-0419 | doi=10.1080/01490419.2013.837849 | pages=1–13 | bibcode=2014MarGe..37....1G | s2cid=128668687 |url=http://ccom.unh.edu/sites/default/files/publications/Gardner-et-al-2014-Challenger-Deep.pdf }}</ref> The deepest point of the trench is more than {{cvt|2|km}} farther from sea level than the peak of [[Mount Everest]].{{efn|Mariana Trench is {{cvt|10,994|m|ft mi}} deep,<ref name=smmt/> while Mount Everest is {{cvt|8,848|m|ft mi}} tall.<ref>{{cite web |title=Official height for Everest set |url=http://news.bbc.co.uk/2/hi/south_asia/8608913.stm |publisher=BBC News |access-date=24 June 2018 |date=8 April 2010}}</ref> The difference is {{cvt|2,146|m|ft mi}}, or at least no less than {{cvt|2,104|m|ft mi}}, accounting for the combined {{cvt|42|m|ft mi}} uncertainty in the measurements.}}

At the bottom of the trench, the [[water column]] above exerts a pressure of {{cvt|1086|bar|psi}}, more than 1,071 times the [[standard atmospheric pressure]] at sea level. At this pressure, the density of water is increased by 4.96%.{{citation needed|date=June 2024}} The temperature at the bottom is {{convert|1|to|4|C|}}.<ref>{{cite web |url=http://www.infoplease.com/askeds/temperature-mariana-trench.html |title=The Temperature in the Mariana Trench |website=Infoplease |date=28 February 2017}}</ref>

In 2009, the Mariana Trench was established as a [[National monument (United States)|US National Monument]], [[Mariana Trench Marine National Monument]].<ref>{{cite web |url=https://www.fws.gov/refuge/Mariana_Trench_Marine_National_Monument/about/About_the_Monument.html |title=About the Monument – Mariana Trench |publisher=U.S. Fish and Wildlife Service}}</ref>

One-celled organisms called [[monothalamea]] have been found in the trench at a record depth of {{cvt|10.6|km|ft mi}} below the [[sea surface]] by researchers from the [[Scripps Institution of Oceanography]].<ref name="gaf">{{Cite news |url=http://latimesblogs.latimes.com/nationnow/2011/10/giant-amoeba-found-mariana-trench-beneath-the-sea.html |title=Giant amoeba found in Mariana Trench – 6.6 miles beneath the sea |access-date=23 March 2012 |date=26 October 2011 |newspaper=Los Angeles Times}}</ref> Data has also suggested that [[microbes|microbial life forms]] thrive within the trench.<ref name="LS-20130317">{{cite web |last=Choi |first=Charles Q. |title=Microbes Thrive in Deepest Spot on Earth |url=http://www.livescience.com/27954-microbes-mariana-trench.html |date=17 March 2013 |publisher=[[LiveScience]] |access-date=17 March 2013}}</ref><ref name="NG-20130317">{{cite journal |last1=Glud |first1=Ronnie |last2=Wenzhöfer |first2=Frank |last3=Middleboe |first3=Mathias |last4=Oguri |first4=Kazumasa |last5=Turnewitsch |first5=Robert |last6=Canfield |first6=Donald E. |last7=Kitazato |first7=Hiroshi |title=High rates of microbial carbon turnover in sediments in the deepest oceanic trench on Earth |doi=10.1038/ngeo1773 |date=17 March 2013 |journal=[[Nature Geoscience]] |volume=6 |issue=4 |pages=284–288 |bibcode=2013NatGe...6..284G}}</ref>

==Etymology==
The Mariana Trench is named after the nearby [[Mariana Islands]], which are named Las Marianas in honor of Spanish Queen [[Mariana of Austria]]. The islands are part of the [[island arc]] that is formed on an over-riding plate, called the Mariana plate (also named for the islands), on the western side of the trench.

==Geology==
[[File:Cross section of mariana trench.svg|right|upright=1.6|thumb|The Pacific plate is subducted beneath the Mariana plate, creating the Mariana trench, and (further on) the arc of the Mariana Islands, as water trapped in the plate is released and explodes upward to form island volcanoes and earthquakes.]]
The Mariana Trench is part of the [[Izu–Bonin–Mariana Arc|Izu–Bonin–Mariana]] [[subduction]] system that forms the [[convergent boundary|boundary]] between two [[tectonic plate]]s. In this system, the western edge of one plate, the [[Pacific plate]], is [[subduction|subducted]] (i.e., thrust) beneath the smaller [[Mariana plate]] that lies to the west. Crustal material at the western edge of the Pacific plate is some of the oldest [[oceanic crust]] on Earth (up to 170 million years old), and is, therefore, cooler and denser; hence its great height difference relative to the higher-riding (and younger) Mariana plate. The deepest area at the plate boundary is the Mariana Trench proper.

The movement of the Pacific and Mariana plates is also indirectly responsible for the formation of the [[Mariana Islands]]. These volcanic islands are caused by [[flux melting]] of the [[upper mantle (Earth)|upper mantle]] due to the release of water that is trapped in minerals of the subducted portion of the [[Pacific plate]].

==Research history==
[[File:Map00148 (28286522445).jpg|thumb|upright=1.0|Ocean trenches in the western Pacific]]
{{See also|Challenger Deep}}
The trench was first [[Depth sounding|sounded]] during the [[Challenger expedition|''Challenger'' expedition]] in 1875 using a weighted rope, which recorded a depth of {{convert|4475|fathom|m ft|abbr=off|lk=in}}.<ref>{{cite web |url=http://deepseachallenge.com/the-expedition/mariana-trench/ |title=About the Mariana Trench – Deepsea Challenge Expedition |publisher=Deepseachallenge.com |date=26 March 2012 |access-date=8 July 2013 |url-status=dead |archive-url=https://web.archive.org/web/20130628083954/http://deepseachallenge.com/the-expedition/mariana-trench/ |archive-date=28 June 2013}}</ref><ref>{{cite book |last1=Aitken |first1=Frédéric |last2=Foulc |first2=Jean-Numa |title=From deep sea to laboratory. 1 : the first explorations of the deep sea by H.M.S. Challenger (1872–1876) |date=2019 |location=London. |isbn=9781786303745 |url=http://www.iste.co.uk/book.php?id=1474 |chapter=Chapter 4}}</ref> In 1877, a map was published called ''Tiefenkarte des Grossen Ozeans'' ("Depth map of the Great Ocean") by Petermann, which showed a ''Challenger Tief'' ("Challenger deep") at the location of that sounding. In 1899, {{USS|Nero|AC-17|6}}, a converted [[Collier (ship)|collier]], recorded a depth of {{convert|5269|fathom|m ft|abbr=off}}.<ref name="Theberge">{{cite web |url=https://www.hydro-international.com/content/article/thirty-years-of-discovering-the-mariana-trench |title=Thirty Years of Discovering the Mariana Trench |last=Theberge |first=A. |date=24 March 2009 |work=Hydro International |access-date=31 July 2010}}</ref>

In 1951, under Chief Scientist [[Thomas Frohock Gaskell|Thomas Gaskell]], ''[[HMS Challenger (1931)|Challenger II]]'' surveyed the trench using [[echo sounding]], a much more precise and vastly easier way to measure depth than the sounding equipment and drag lines used in the original expedition. During this survey, the deepest part of the trench was recorded when the ''Challenger II'' measured a depth of {{convert|5960|fathom|m ft|abbr=off}} at {{Coord|11|19|N|142|15|E}},<ref>{{Cite book |last=Gaskell |first=Thomas F. |title=Under The Deep Oceans: Twentieth Century Voyages of Discovery |publisher=Eyre & Spottiswood |year=1960 |edition=1st |pages=121}}</ref> known as the [[Challenger Deep]].<ref name="marianatrench.com">{{cite web |url=http://www.marianatrench.com/mariana_trench-exploration_001.htm |title=The Mariana Trench – Exploration |publisher=marianatrench.com}}</ref>

In 1957, the [[Soviet Union|Soviet]] vessel {{ship|RV|Vityaz|1939|2}} reported a depth of {{cvt|11034|m|ft fathom}} at a location dubbed the ''Mariana Hollow''.<ref name="mariana_britannica">{{cite encyclopedia |title=Mariana Trench |encyclopedia=Encyclopædia Britannica |date=18 July 2023 |url=https://www.britannica.com/place/Pacific-Ocean}}</ref>{{better source needed|date=October 2022}}<!-- Uncalibrated and later recanted by the original author-->

In 1962, the surface ship M.V. ''Spencer F. Baird'' recorded a maximum depth of {{cvt|10915|m|ft fathom}} using precision [[depth gauge]]s.

In 1984, the Japanese survey vessel ''Takuyō'' (拓洋) collected data from the Mariana Trench using a narrow, multi-beam echo sounder; it reported a maximum depth of {{convert|10924|m}}, also reported as {{cvt|10920|±|10|m|ft fathom}}.<ref name="Tani">{{cite web |url=http://www.gmat.unsw.edu.au/ablos/ABLOS08Folder/Session4-Paper4-Tani.pdf |title=Continental shelf survey of Japan |last=Tani |first=S. |access-date=24 December 2010 |url-status=dead |archive-url=https://web.archive.org/web/20110309013717/http://www.gmat.unsw.edu.au/ablos/ABLOS08Folder/Session4-Paper4-Tani.pdf |archive-date=9 March 2011 }}</ref> Remotely Operated Vehicle ''[[Kaikō ROV|KAIKO]]'' reached the deepest area of the Mariana Trench and made the deepest diving record of {{cvt|10911|m|ft fathom}} on 24 March 1995.<ref>[http://www.mhi.co.jp/technology/review/abstractj-32-6-427.html Development and Construction of Launcher System of 10000m‐Class Remotely Operated Vehicle KAIKO] {{Webarchive|url=https://web.archive.org/web/20150402104327/http://www.mhi.co.jp/technology/review/abstractj-32-6-427.html |date=2 April 2015 }} Mitsubishi Heavy Industry</ref>

During surveys carried out between 1997 and 2001, a spot was found along the Mariana Trench that had a depth similar to the Challenger Deep, possibly even deeper. It was discovered while scientists from the [[University of Hawaii|Hawaii Institute of Geophysics and Planetology]] were completing a survey around [[Guam]]; they used a sonar mapping system towed behind the research ship to conduct the survey. This new spot was named the [[HMRG Deep|HMRG (Hawaii Mapping Research Group) Deep]], after the group of scientists who discovered it.<ref>{{cite news |title=Sea floor survey reveals deep hole |first=David |last=Whitehouse |url=http://news.bbc.co.uk/2/hi/science/nature/3071749.stm |publisher=BBC News |date=16 July 2003 |access-date=17 December 2011}}</ref>

On 1 June 2009, mapping aboard the {{ship|RV|Kilo Moana}} (mothership of the Nereus vehicle), indicated a spot with a depth of {{cvt|10971|m|ft fathom|0}}. The sonar mapping of the Challenger Deep was possible by its Simrad EM120 sonar multibeam bathymetry system for deep water. The sonar system uses phase and amplitude bottom detection, with an accuracy of better than 0.2% of water depth across the entire swath (implying that the depth figure is accurate to ± {{convert|22|m|ft fathom}}).<ref name="Daily Reports for R/V KILO MOANA">{{Cite news |url=http://www.soest.hawaii.edu/UMC/Reports/Archives/KMreportJuneJuly2009.html |title=Daily Reports for R/V KILO MOANA June and July 2009 |publisher=University of Hawaii Marine Center |url-status=dead |archive-url=https://web.archive.org/web/20100121061243/http://www.soest.hawaii.edu/UMC/Reports/Archives/KMreportJuneJuly2009.html |archive-date=21 January 2010 |access-date=4 January 2010 }}</ref><ref name="Scientic Equipment aboard the R/V KILO MOANA">{{Cite news |url=http://www.soest.hawaii.edu/UMC/KM/scienceequipment.htm |title=Inventory of Scientific Equipment aboard the R/V KILO MOANA |publisher=University of Hawaii Marine Center |url-status=dead |archive-url=https://web.archive.org/web/20100613143513/http://www.soest.hawaii.edu/UMC/KM/scienceequipment.htm |archive-date=13 June 2010 }}</ref>

In 2011, it was announced at the [[American Geophysical Union]] Fall Meeting that a US Navy hydrographic ship equipped with a [[multibeam echosounder]] conducted a survey which mapped the entire trench to {{cvt|100|m|ft fathom}} resolution.<ref name="smmt">{{Cite news |url=https://www.telegraph.co.uk/news/earth/environment/8940571/Scientists-map-Mariana-Trench-deepest-known-section-of-ocean-in-the-world.html |archive-url=https://ghostarchive.org/archive/20220110/https://www.telegraph.co.uk/news/earth/environment/8940571/Scientists-map-Mariana-Trench-deepest-known-section-of-ocean-in-the-world.html |archive-date=10 January 2022 |url-access=subscription |url-status=live |title=Scientists map Mariana Trench, deepest known section of ocean in the world |access-date=23 June 2018 |date=7 December 2011 |newspaper=The Telegraph }}{{cbignore}}</ref> The mapping revealed the existence of four rocky outcrops thought to be former [[seamount]]s.<ref name="fourbrid">{{Cite magazine |url=https://www.wired.co.uk/news/archive/2012-02/07/bridges-mariana-trench |title=Four 'bridges' span the Mariana Trench |author=Duncan Geere |access-date=23 March 2012 |date=7 February 2012 |magazine=Wired |url-status=dead |archive-url=https://web.archive.org/web/20120311150303/http://www.wired.co.uk/news/archive/2012-02/07/bridges-mariana-trench |archive-date=11 March 2012 }}</ref>

The Mariana Trench was a site chosen by researchers at [[Washington University in St. Louis]] and the [[Woods Hole Oceanographic Institution]] in 2012 for a seismic survey to investigate the subsurface [[water cycle]]. Using both [[ocean-bottom seismometer]]s and [[hydrophone]]s, the scientists were able to map structures as deep as {{convert|97|km|ft fathom mile}} beneath the surface.<ref name="ssatmt">{{Cite news |url=https://www.sciencedaily.com/releases/2012/03/120322142201.htm |title=Seismic Survey at the Mariana Trench Will Follow Water Dragged Down into the Earth's Mantle |access-date=23 March 2012 |date=22 March 2012 |work=ScienceDaily}}</ref>

===Descents===
{{Update|section|date=June 2020}}
[[File:Bathyscaphe Trieste.jpg|thumb|The [[bathyscaphe]] ''[[Trieste (bathyscaphe)|Trieste]]'' (designed by [[Auguste Piccard]]), the first crewed vehicle to reach the bottom of the Mariana Trench<ref>{{cite web |url=https://spectrum.ieee.org/don-walsh-describes-the-trip-to-the-bottom-of-the-mariana-trench |title=Don Walsh Describes the Trip to the Bottom of the Mariana Trench |publisher=[[IEEE Spectrum]] |last=Strickland |first=Eliza |date=29 February 2012 |access-date=8 July 2013}}</ref>]]

As of 2022, 22 crewed descents and seven uncrewed descents have been achieved. The first was the crewed descent by Swiss-designed, Italian-built, [[United States Navy]]-owned [[bathyscaphe]] ''[[Trieste (bathyscaphe)|Trieste]]'', which reached the bottom at 1:06&nbsp;pm on 23 January 1960, with [[Don Walsh]] and [[Jacques Piccard]] on board.<ref name="marianatrench.com" /><ref name="eahapr"/> Iron shot was used for [[Sailing ballast|ballast]], with [[gasoline]] for [[buoyancy]].<ref name="marianatrench.com" /> The onboard systems indicated a depth of {{convert|37800|ft|m fathom|0}},<ref name=NOAA_Man_at_the_Deepest_Depth>{{cite web |url=http://oceanexplorer.noaa.gov/history/quotes/soundings/soundings.html |title=NOAA Ocean Explorer: History: Quotations: Soundings, Sea-Bottom, and Geophysics |publisher=[[NOAA]] Ocean Exploration and Research}}</ref> but this was later revised to {{convert|35814|ft|m fathom|0}}.<ref name="britannica-bathyscaphe">{{cite encyclopedia |url=https://www.britannica.com/technology/bathyscaphe |title=Bathyscaphe |encyclopedia=[[Encyclopædia Britannica]] |date=18 April 2020 |access-date=11 November 2020}}</ref> The depth was estimated from a conversion of [[pressure]] measured and calculations based on the [[Density of saltwater|water density]] from sea surface to seabed.<ref name="eahapr">{{cite web |url=https://earthquake.usgs.gov/earthquakes/world/guam/mariana_trench.php |title=Mariana Trench |date=21 October 2009 |publisher=United States Geological Survey |access-date=23 March 2012 |url-status=dead |archive-url=https://web.archive.org/web/20120318064310/http://earthquake.usgs.gov/earthquakes/world/guam/mariana_trench.php |archive-date=18 March 2012 }}</ref>

This was followed by the uncrewed [[Remotely operated underwater vehicle|ROVs]] ''[[Kaikō ROV|Kaikō]]'' in 1996 and [[Nereus (underwater vehicle)|''Nereus'']] in 2009. The first three expeditions directly measured very similar depths of {{cvt|10902|to|10916|m|ft fathom}}.<ref name="jamstec">{{cite web |url=http://www.jamstec.go.jp/e/about/equipment/ships/kaiko7000.html |title=7,000 m Class Remotely Operated Vehicle: KAIKO 7000 |publisher=[[Japan Agency for Marine-Earth Science and Technology]] |access-date=11 November 2020 |archive-date=10 April 2020 |archive-url=https://web.archive.org/web/20200410211118/http://www.jamstec.go.jp/e/about/equipment/ships/kaiko7000.html |url-status=dead }}</ref><ref name="bbc20090603">{{cite news |url=http://news.bbc.co.uk/2/hi/science/nature/8080324.stm |title=Robot sub reaches deepest ocean |publisher=BBC |date=3 June 2009 |access-date=11 November 2020}}</ref> The fourth was made by Canadian film director [[James Cameron]] on 26 March 2012. He reached the bottom of the Mariana Trench in the submersible vessel ''[[Deepsea Challenger]]'', diving to a depth of {{cvt|10908|m|ft fathom}}.<ref>{{Cite news |url=https://www.cbc.ca/news/world/trash-littering-ocean-floor-deepest-submarine-dive-1.5134717 |title=A man took a submarine to the deepest place on Earth – and found trash |publisher=[[CBC.ca]] |agency=[[Thomson Reuters]] |date=13 May 2019 |access-date=11 November 2020}}</ref><ref name="MSNBC-20120325">{{cite news |url=https://www.nbcnews.com/id/wbna46850002 |title=James Cameron has reached deepest spot on Earth |publisher=[[NBC News]] |date=25 March 2012 |access-date=25 March 2012}}</ref><ref name="NYT-20120325">{{cite news |url=https://www.nytimes.com/2012/03/26/science/james-camerons-submarine-trip-to-challenger-deep.html |title=Filmmaker in Submarine Voyages to Bottom of Sea |work=The New York Times |first=William J. |last=Broad |date=25 March 2012 |access-date=25 March 2012}}</ref>

In July 2015, members of the National Oceanic and Atmospheric Administration, Oregon State University, and the Coast Guard submerged a hydrophone into the deepest part of the Mariana Trench, the Challenger Deep, never having previously deployed one past a mile. The titanium-shelled hydrophone was designed to withstand the immense pressure {{cvt|7|miles|ft fathom m}} under.<ref name="newscomau20160307">{{cite news |url=https://www.news.com.au/travel/destinations/eerie-sounds-from-the-bottom-of-the-earth/news-story/53fffdfcb549bfcb80c4ea8833b7968b |title=Eerie sounds from the bottom of the Earth |work=[[News.com.au]] |first=Kate |last=Schneider |date=7 March 2016 |access-date=11 November 2020}}</ref> Although researchers were unable to retrieve the hydrophone until November, the data capacity was full within the first 23 days. After months of analyzing the sounds, the experts were surprised to pick up natural sounds like [[earthquakes]], [[typhoons]], [[whale|baleen whales]], and machine-made sounds such as boats.<ref name="NPR4Mar2016">{{cite news |url=https://www.npr.org/sections/thetwo-way/2016/03/04/469213580/unique-audio-recordings-find-a-noisy-mariana-trench-and-surprise-scientists |title=Deep-Sea Audio Recordings Reveal A Noisy Mariana Trench, Surprising Scientists |publisher=[[NPR]] |last=Chappell |first=Bill |date=4 March 2016 |access-date=1 May 2016}}</ref> Due to the mission's success, the researchers announced plans to deploy a second hydrophone in 2017 for an extended period of time.

[[Victor Vescovo]] achieved a new record descent to {{cvt|10928|m|ft fathom}} on 28 April 2019 using the DSV ''Limiting Factor'', a Triton 36000/2 model manufactured by Florida-based [[Triton Submarines]]. He dived four times between 28 April and 5 May 2019, becoming the first person to dive into Challenger Deep more than once.<ref name="fivedeep20190513">{{cite web |url=https://fivedeeps.com/wp-content/uploads/2019/05/FDE-Challenger-Release-FINAL-5132019.pdf |title=Deepest Submarine Dive in history, Five Deeps Expedition Conquers Challenger Deep |publisher=The Five Deeps |first=Stephanie |last=Fitzherbert |date=13 May 2019 |access-date=11 November 2020}}</ref><ref name="eos20190703">{{cite news |url=https://eos.org/articles/limiting-factor-was-a-science-opportunity-for-a-deep-sea-geologist |title=''Limiting Factor'' Was a Science Opportunity for a Deep-Sea Geologist |work=[[Eos (magazine)|Eos]] |first=Ilima |last=Loomis |date=3 July 2019 |access-date=11 November 2020}}</ref><ref name="newat20190515">{{cite news |url=https://newatlas.com/five-deeps-dsv-limiting-factor-mariana-trench/59690/ |title=Victor Vescovo and the DSV Limiting Factor have found new depths in the Mariana Trench |work=New Atlas |first=Loz |last=Blain |date=15 May 2019 |access-date=11 November 2020}}</ref>

On 8 May 2020, a joint project between the Russian shipbuilders, scientific teams of the [[Russian Academy of Sciences]] with the support of the [[Russian Foundation for Advanced Research Projects in the Defense Industry|Russian Foundation for Advanced Research Projects]] and the [[Pacific Fleet (Russia)|Pacific Fleet]] submerged the [[autonomous underwater vehicle]] ''Vityaz-D'' to the bottom of the Mariana Trench at a depth of {{cvt|10028|m|ft fathom}}. ''[[Vityaz-D Autonomous Underwater Vehicle|Vityaz-D]]'' is the first underwater vehicle to operate autonomously at the extreme depths of the Mariana Trench. The duration of the mission, excluding diving and surfacing, was more than 3 hours.<ref name="rgo20200513">{{cite web |url=https://www.rgo.ru/en/article/russian-submarine-vityaz-reached-bottom-mariana-trench |title=Russian Submarine "Vityaz" Reached the Bottom of the Mariana Trench |publisher=[[Russian Geographical Society]] |date=13 May 2020 |access-date=11 November 2020}}</ref><ref name="tass20200610">{{cite news |url=https://tass.com/defense/1166477 |title=Vityaz-D explored Mariana Trench according to preinstalled program – developer |work=[[TASS]] |date=10 June 2020 |access-date=11 November 2020}}</ref>

On 10 November 2020, the Chinese submersible [[Struggler (bathyscaphe)|''Fendouzhe'']] reached the bottom of the Mariana Trench at a depth of {{cvt|10909|m|ft fathom}}.<ref name="cnn20201111">{{cite news |url=https://edition.cnn.com/2020/11/11/asia/china-record-dive-mariana-trench-intl-hnk/ |title=China breaks national record for Mariana Trench manned-dive amid race for deep sea resources |publisher=CNN|first=Ben |last=Westcott |date=11 November 2020 |access-date=11 November 2020 |archive-url=https://web.archive.org/web/20201111184811/https://edition.cnn.com/2020/11/11/asia/china-record-dive-mariana-trench-intl-hnk/ |archive-date=11 November 2020}}</ref><ref name="cctv20201110">{{cite news |url=https://news.cctv.com/2020/11/10/ARTIQc1R6lp4IlMJT8G3SNqY201110.shtml |title="奋斗者"号载人潜水器突破万米海深 潜入全球最深海域 |trans-title=The "Striver" manned submersible breaks through 10,000 meters and dives into the world's deepest waters |publisher=[[China Central Television]] |first1=Xiang |last1=Cheng |first2=Liang |last2=Liu |date=10 November 2020 |access-date=11 November 2020}}</ref>

== Life ==
The expedition conducted in 1960 claimed to have observed, with great surprise because of the high pressure, large creatures living at the bottom, such as a [[flatfish]] about {{cvt|30|cm|in|0}} long,<ref name="NOAA_Man_at_the_Deepest_Depth"/> and [[shrimp]].<ref>{{cite web |url=http://geology.com/records/bathyscaphe-trieste.shtml |title=Bathyscaphe Trieste &#124; Mariana Trench &#124; Challenger Deep |publisher=Geology.com |access-date=1 March 2012}}</ref> According to Piccard, "The bottom appeared light and clear, a waste of firm [[diatom]]aceous ooze".<ref name=NOAA_Man_at_the_Deepest_Depth/> Many marine biologists are now skeptical of the supposed sighting of the flatfish, and it is suggested that the creature may instead have been a [[sea cucumber]].<ref>[https://www.theguardian.com/environment/2011/jan/18/james-cameron-dives-deep-avatar "James Cameron dives deep for Avatar"] {{Webarchive|url=https://web.archive.org/web/20170118064643/https://www.theguardian.com/environment/2011/jan/18/james-cameron-dives-deep-avatar |date=18 January 2017 }}, ''Guardian'', 18 January 2011</ref><ref>[http://www.nature.com/news/james-cameron-heads-into-the-abyss-1.10246 "James Cameron heads into the abyss"] {{Webarchive|url=https://web.archive.org/web/20120901025830/http://www.nature.com/news/james-cameron-heads-into-the-abyss-1.10246 |date=1 September 2012 }}, ''Nature'', 19 March 2012</ref> During the second expedition, the uncrewed vehicle ''[[Kaikō ROV|Kaikō]]'' collected mud samples from the [[seabed]].<ref name="snw">{{cite book |title=Seven Natural Wonders of the Arctic, Antarctica, and the Oceans |last=Woods |first=Michael |author2=Mary B. Woods |year=2009 |publisher=Twenty-First Century Books |isbn=978-0-8225-9075-0 |page=[https://archive.org/details/sevennaturalwond0000wood_u5g0/page/13 13] |url=https://archive.org/details/sevennaturalwond0000wood_u5g0 |url-access=registration |access-date=23 March 2012}}</ref> Tiny organisms were found to be living in those samples.

In July 2011, a research expedition deployed untethered landers, called drop cams, equipped with digital video cameras and lights to explore this deep-sea region. Among many other living organisms, some gigantic single-celled foraminiferans with a size of more than {{Convert|4|in|cm|abbr=on|order=flip}}, belonging to the class of [[monothalamea]], were observed.<ref>{{cite web |url=http://www.livescience.com/16678-giant-amoebas-discovered-deepest-ocean-trench.html |title=Giant amoebas discovered in the deepest ocean trench |website=[[Live Science]] |date=21 October 2011 |access-date=26 March 2012}}</ref> Monothalamea are noteworthy for their size, their extreme abundance on the seafloor, and their role as hosts for a variety of organisms.

In December 2014, a new species of [[snailfish]] was discovered at a depth of {{cvt|8145|m|ft fathom}}, breaking the previous record for the deepest living fish seen on video.<ref name=BBCDeept>{{cite web |title=New record for deepest fish |url=https://www.bbc.co.uk/news/science-environment-30541065 |first=Rebecca |last=Morelle |author-link=Rebecca Morelle |publisher=BBC News |date=9 December 2014 |access-date=26 August 2017}}</ref>

During the 2014 expedition, several new species were filmed, including huge [[Amphipoda|amphipods]] known as supergiants. [[Deep-sea gigantism]] is the process where species grow larger than their shallow-water relatives.<ref name=BBCDeept/>

In May 2017, an unidentified type of snailfish was filmed at a depth of {{Convert|8178|m|ft|-2}}.<ref>{{cite news |url=https://www.cbc.ca/news/technology/deepest-fish-1.4263003 |title=Ghostly fish in Mariana Trench in the Pacific is deepest ever recorded |work=[[CBC News]] |date=25 August 2017 |access-date=26 August 2017}}</ref>

===Pollution===
In 2016, a research expedition looked at the chemical makeup of crustacean scavengers collected from the range of {{cvt|7,841|-|10,250|m|ft fathom}} within the trench. Within these organisms, the researchers found extremely elevated concentrations of [[Polychlorinated biphenyl|PCBs]], a chemical toxin banned in the 1970s for its environmental harm, concentrated at all depths within the sediment of the trench.<ref>{{Cite journal |last1=Jamieson |first1=Alan J. |last2=Malkocs |first2=Tamas |last3=Piertney |first3=Stuart B. |last4=Fujii |first4=Toyonobu |last5=Zhang |first5=Zulin |date=13 February 2017 |title=Bioaccumulation of persistent organic pollutants in the deepest ocean fauna |journal=Nature Ecology & Evolution |volume=1 |issue=3 |page=51 |doi=10.1038/s41559-016-0051 |pmid=28812719 |issn=2397-334X |hdl=2164/9142 |s2cid=9192602 |hdl-access=free}}</ref> Further research has found that amphipods also ingest [[microplastics]], with 100% of amphipods having at least one piece of synthetic material in their stomachs.<ref>{{Cite journal |last1=Jamieson |first1=A. J. |last2=Brooks |first2=L. S. R. |last3=Reid |first3=W. D. K. |last4=Piertney |first4=S. B. |last5=Narayanaswamy |first5=B. E. |last6=Linley |first6=T. D. |date=28 February 2019 |title=Microplastics and synthetic particles ingested by deep-sea amphipods in six of the deepest marine ecosystems on Earth |journal=Royal Society Open Science |volume=6 |issue=2 |pages=180667 |doi=10.1098/rsos.180667 |pmid=30891254 |issn=2054-5703 |pmc=6408374 |bibcode=2019RSOS....680667J}}</ref><ref>{{Cite web |url=https://www.latimes.com/california/story/2019-09-04/uc-san-diego-discovers-explosion-in-plastics-products-in-seafloor-off-santa-barbara |title=UCSD discovers surge in plastics pollution off Santa Barbara |last=Robbins |first=Gary |date=5 September 2019 |website=Los Angeles Times |access-date=5 September 2019}}</ref>

In 2019, Victor Vescovo reported finding a plastic bag and candy wrappers at the bottom of the trench.<ref name="CNNMay2019">{{cite news |last1=Street |first1=Francesca |title=Deepest ocean dive recorded: How Victor Vescovo did it |url=https://www.cnn.com/travel/article/victor-vescovo-deepest-dive-pacific/index.html |access-date=13 May 2019 |publisher=CNN Travel|date=13 May 2019}}</ref> That year, ''[[Scientific American]]'' also reported that [[carbon-14]] from nuclear bomb testing has been found in the bodies of aquatic animals found in the trench.<ref>{{cite news |url=https://www.scientificamerican.com/article/bomb-carbon-has-been-found-in-deep-ocean-creatures/ |title="Bomb Carbon" Has Been Found in Deep-Ocean Creatures |work=[[Scientific American]] |first=Adam |last=Levy |date=15 May 2019}}</ref>

==Possible nuclear waste disposal site==
Like other oceanic trenches, the Mariana Trench has been proposed as a site for [[radioactive waste#dispose|nuclear waste disposal]]<ref name="isbn0-387-95560-7"/><ref name="isbn0-7546-7133-X"/> in the hope that tectonic plate [[subduction]] occurring at the site might eventually push the nuclear waste deep into the [[Earth's mantle]], the second layer of the Earth. In 1979 Japan planned to dump low-level nuclear wastes near Maug, in the Northern Marianas.<ref>Branch, J. B. (1984). [https://www2.kobe-u.ac.jp/~alexroni/TR2017%20Readings/TR_2017_11/The%20Waste%20Bin.pdf The waste bin: nuclear waste dumping and storage in the Pacific]. Ambio, 327-330.</ref> However, ocean dumping of nuclear waste is prohibited by international law.<ref name="isbn0-387-95560-7">{{cite book |author=Hafemeister, David W. |title=Physics of societal issues: calculations on national security, environment, and energy |publisher=Springer |location=Berlin |year=2007 |page=187 |isbn=978-0-387-95560-5 |url=https://books.google.com/books?id=LT4MSqv9QUIC&pg=PA187}}</ref><ref name="isbn0-7546-7133-X">{{cite book |author1=Kingsley, Marvin G. |author2=Rogers, Kenneth H. |title=Calculated risks: highly radioactive waste and homeland security |publisher=Ashgate |location=Aldershot, Hants, England |year=2007 |pages=75–76 |isbn=978-0-7546-7133-6 |url=https://books.google.com/books?id=bOP4-BpYXrEC&pg=PA75}}</ref><ref>{{cite web |url=http://www.law.berkeley.edu/centers/ilr/ona/pages/dumping2.htm |title=Dumping and Loss overview |work=Oceans in the Nuclear Age |access-date=18 September 2010 |archive-url=https://web.archive.org/web/20110605190619/http://www.law.berkeley.edu/centers/ilr/ona/pages/dumping2.htm |archive-date=5 June 2011}}</ref> Furthermore, plate subduction zones are associated with very large [[megathrust earthquake]]s, the effects of which are unpredictable for the safety of long-term disposal of nuclear wastes within the [[hadopelagic]] [[ecosystem]].<ref name="isbn0-7546-7133-X"/>

==See also==
{{Portal|Oceania}}
* [[Mariana Trench Marine National Monument]], United States national monument at the trench. This National Monument protects {{Convert|95216|mi2|order=flip}} of submerged lands and waters of the Mariana Archipelago. It includes some of the Mariana Trench, but not the deepest part, the [[Challenger Deep]], which lies just outside the monument area.
* [[List of people who descended to Challenger Deep]]
* [[Litke Deep]], closest point to Earth's center

==Notes==
{{notelist}}

==References==
{{Reflist}}

==External links==
{{Commons category|Mariana Trench}}
*[https://web.archive.org/web/20140625050833/http://deepseachallenge.com/ Mariana Trench Dive (25 March 2012)] – [[Deepsea Challenger]]
*[http://www.britishpathe.com/video/they-dived-7-miles/query/mariana+trench Mariana Trench Dive (23 January 1960)] – [[Bathyscaphe Trieste|Trieste]] (Newsreel)
*[http://www.vvdailypress.com/articles/walsh-18116-regret-miles.html Mariana Trench Dive (50th Anniv)] {{Webarchive|url=https://web.archive.org/web/20130603064615/http://www.vvdailypress.com/articles/walsh-18116-regret-miles.html |date=3 June 2013 }} – [[Bathyscaphe Trieste|Trieste]] – [[Don Walsh|Capt Don Walsh]]
*[https://maps.google.com/maps?q=11.317,+142.25(Mariana+Trench)&z=6 Mariana Trench – Maps (Google)]
*[http://oceanexplorer.noaa.gov NOAA – Ocean Explorer] (Ofc Ocean Exploration & Rsch)
*[http://oceanexplorer.noaa.gov/explorations/06fire/background/marianaarc/marianaarc.html NOAA – Ocean Explorer – Multimedia] – [[Izu–Bonin–Mariana Arc|Mariana Arc]] ([http://oceanexplorer.noaa.gov/explorations/podcast/oceanexplorer_podcast.xml podcast])
*[https://www.youtube.com/view_play_list?p=94B795FD631011E0 NOAA – Ocean Explorer – Video Playlist] – [[Ring of Fire]] (2004–2006)

{{East Asia plates}}
{{Authority control}}

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[[Category:Philippine Sea]]
[[Category:Oceanic trenches of the Pacific Ocean]]
[[Category:Extreme points of Earth]]
[[Category:Subduction zones]]
[[Category:Lowest points of the World Ocean]]