Editing Challenger Deep (section)

====1996 and 1998 – ''Kaikō''====
{{Main|Kaikō ROV}}

The remotely operated vehicle (ROV) ''Kaikō'' made many uncrewed descents to the Mariana Trench from its support ship RV ''Yokosuka'' during two expeditions in 1996 and 1998.<ref>{{cite web|url=https://www.mbari.org/wp-content/uploads/2016/01/Barry-and-Hashimoto-Challenger-deep-2009.pdf |archive-url=https://web.archive.org/web/20161220205139/https://www.mbari.org/wp-content/uploads/2016/01/Barry-and-Hashimoto-Challenger-deep-2009.pdf |archive-date=2016-12-20 |url-status=live |title=Revisiting the Challenger Deep using the ROV Kaiko |publisher=Winter 2009 Volume 43, Number 5 |access-date=15 December 2016}}</ref>
From 29 February to 4 March the ROV ''Kaiko'' made three dives into the ''central'' basin, ''Kaiko'' #21 – ''Kaiko'' #23, . Depths ranged from {{convert|10898|m|ft}} at {{Coord|11|22.536|N|142|26.418|E}}, to {{convert|10896|m|ft}} at {{Coord|11|22.59|N|142|25.848|E}}; dives #22 & #23 to the north, and dive #21 northeast of the deepest waters of the ''central'' basin.<ref>{{cite web| url = http://www.godac.jamstec.go.jp/darwin/dive/kaiko/21/e| title = Partial suspension of access to the data and services on our website < About JAMSTEC < JAMSTEC| access-date = 17 November 2019| archive-date = 17 November 2019| archive-url = https://web.archive.org/web/20191117232748/http://www.godac.jamstec.go.jp/darwin/dive/kaiko/21/e| url-status = live}}</ref> During the 1996 measurements the temperature (water temperature increases at great depth due to adiabatic compression), [[salinity]] and water pressure at the sampling station was {{convert|2.6|°C|°F}}, 34.7‰ and {{convert|1113|bar|MPa psi|abbr=on}}, respectively at {{convert|10897|m|0|abbr=on}} depth.<ref name="Akimoto">{{Cite journal| author=Akimoto | title=The deepest living foraminifera, Challenger Deep, Mariana Trench | journal=Marine Micropaleontology | volume=42 | issue=1–2 | year=2001 | page=95 | doi=10.1016/S0377-8398(01)00012-3|display-authors=etal| bibcode=2001MarMP..42...95A}}</ref> The Japanese robotic deep-sea probe ''Kaikō'' broke the depth record for uncrewed probes when it reached close to the surveyed bottom of the Challenger Deep. Created by the [[Japan Agency for Marine-Earth Science and Technology|Japan Agency for Marine-Earth Science and Technology (JAMSTEC)]], it was one of the few uncrewed deep-sea probes in operation that could dive deeper than {{convert|6000|m}}. The manometer measured depth of {{convert|10911.4|m|0|abbr=on}} ±{{convert|3|m|ft|0|abbr=on}} at {{Coord|11|22.39|N|142|35.54|E}} for the Challenger Deep is believed to be the most accurate measurement taken up to then.<ref>{{cite web |url=http://www.jamstec.go.jp/e/about/equipment/ships/kaiko7000.html |title=Kaiko 7000II |publisher=Japan Agency for Marine-Earth Science and Technology – note: this ref. contains a date error |access-date=26 March 2012 |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=live }}</ref><ref name="Bathymetric mapping of the world's deepest seafloor, Challenger Deep"/>
Another source states the greatest depth measured by ''Kaikō'' in 1996 was {{convert|10898|m|0|abbr=on}} at {{Coord|11|22.10|N|142|25.85|E}} and {{convert|10907|m|0|abbr=on}} at {{Coord|11|22.95|N|142|12.42|E}} in 1998.<ref name="Bathymetric mapping of the world's deepest seafloor, Challenger Deep"/>
The ROV ''Kaiko'' was the first vehicle to visit to the bottom of the Challenger Deep since the bathyscaph ''Trieste'''s dive in 1960, and the first success in sampling the trench bottom sediment/mud, from which ''Kaiko'' obtained over 360 samples.<ref>Nakanishi, M., "A Precise Bathymetric map of the World's deepest seafloor, Challenger Deep in the Mariana Trench," Marine Geophysical Research, Table 2, 2011, p. 1</ref> Approximately 3,000 different microbes were identified in the samples.<ref>Cruise Summary, YK09-08, Taishi Tsubouchi "Challenger Area" p. 11</ref><ref name="ngnews">[http://news.nationalgeographic.com/news/2005/02/0203_050203_deepest.html "Life Is Found Thriving at Ocean's Deepest Point"] {{Webarchive|url=https://web.archive.org/web/20120822121902/http://news.nationalgeographic.com/news/2005/02/0203_050203_deepest.html |date=22 August 2012 }}, National Geographic News, 3 February 2005</ref><ref name="Akimoto"/>
''Kaikō'' was lost at sea off [[Shikoku|Shikoku Island]] during [[2003 Pacific typhoon season#Typhoon Chan-hom|Typhoon Chan-Hom]] on 29 May 2003.