Editing Challenger Deep (section)

====1960 – ''Trieste''====
{{Main|Bathyscaphe Trieste}}
On 23 January 1960, the Swiss-designed [[Bathyscaphe Trieste|''Trieste'']], originally built in Italy and acquired by the [[United States Navy|U.S. Navy]], supported by the USS ''Wandank'' (ATF 204) and escorted by the USS ''Lewis'' (DE 535), descended to the ocean floor in the trench piloted by [[Jacques Piccard]] (who co-designed the submersible along with his father, [[Auguste Piccard]]) and USN Lieutenant [[Don Walsh]]. Their crew compartment was inside a spherical pressure vessel – measuring 2.16 metres in diameter suspended beneath a buoyancy tank 18.4 metres in length<ref name=":0">{{Cite web|url=https://www.smh.com.au/environment/descent-to-challenger-deep-20110413-1ddnq.html|title=Descent to Challenger Deep|last=Kwek|first=Glenda|date=13 April 2011|website=The Sydney Morning Herald|language=en|access-date=31 July 2019|archive-date=31 July 2019|archive-url=https://web.archive.org/web/20190731175727/https://www.smh.com.au/environment/descent-to-challenger-deep-20110413-1ddnq.html|url-status=live}}</ref> – which was a heavy-duty replacement (of the Italian original) built by [[Krupp]] Steel Works of [[Essen]], [[Germany]]. The [[steel]] walls were {{cvt|12.7|cm|in}} thick and designed to withstand pressure of up to {{convert|1250|kg/cm2|psi atm MPa|abbr=out|comma=off}}.<ref name=":0" />
Their descent took almost five hours and the two men spent barely twenty minutes on the ocean floor before undertaking the three-hour-and-fifteen-minute ascent. Their early departure from the [[Seabed|ocean floor]] was due to their concern over a crack in the outer window caused by the temperature differences during their descent.<ref name="National Geographics">{{cite web |url=http://deepseachallenge.com/the-expedition/1960-dive/ |title=1960 Dive - DEEPSEA CHALLENGE Expedition |access-date=10 April 2012 |url-status=dead |archive-url=https://web.archive.org/web/20120414093239/http://deepseachallenge.com/the-expedition/1960-dive/ |archive-date=14 April 2012}}</ref>

''Trieste'' dived at/near {{Coord|11|18.5|N|142|15.5|E}}, bottoming at {{convert|10911|m|ft}} ±{{convert|7|m|ft|0|abbr=on}} into the Challenger Deep's ''western'' basin, as measured by an onboard [[manometer]].<ref>Piccard, J. "Seven Miles Deep," ''G.P. Putnam's Sons'', 1961, p. 242</ref> Another source states the measured depth at the bottom was measured with a [[manometer]] at {{convert|10913|m|0|abbr=on}} ±{{convert|5|m|ft|0|abbr=on}}.<ref name="Bathymetric mapping of the world's deepest seafloor, Challenger Deep" /><ref name="usn1960">{{cite web
|author=Press Release, Office of Naval Research
|date=1 February 1960
|url=http://www.onr.navy.mil/focus/ocean/vessels/submersibles11.htm
|title=Research Vessels: Submersibles – ''Trieste''
|publisher=United States Navy
|access-date=16 May 2010
|url-status=dead
|archive-url=https://web.archive.org/web/20020418105908/http://www.onr.navy.mil/focus/ocean/vessels/submersibles11.htm
|archive-date=18 April 2002
}}</ref>
Navigation of the support ships was by celestial and [[LORAN-C]] with an accuracy of {{convert|460|m|ft}} or less.<ref name="jproc.ca"/> Fisher noted that the ''Trieste'''s reported depth "agrees well with the sonic sounding."<ref>Fisher, Trenches, ''The Earth Beneath the Sea'', p. 416</ref>