Editing Challenger expedition (section)

== Challenger Deep ==
On 23 March 1875, at sample station number 225 located in the southwest Pacific Ocean between Guam and Palau, the crew recorded a sounding of {{convert|4475|fathom}},<ref name="Aitken_t1" /> which was confirmed by a second sounding.<ref>{{cite web|url=http://www.19thcenturyscience.org/HMSC/HMSC-Reports/1895-Summary/htm/doc877.html|title=Report on the scientific results of the voyage of H.M.S. Challenger during the years of 1872–76 (page 877)|publisher=19thcenturyscience.org|access-date=26 March 2012|archive-date=17 April 2012|archive-url=https://web.archive.org/web/20120417095912/http://www.19thcenturyscience.org/HMSC/HMSC-Reports/1895-Summary/htm/doc877.html|url-status=live}}</ref> As shown by later expeditions using modern equipment, this area represents the southern end of the [[Mariana Trench]] and is one of the deepest known places on the ocean floor.

Modern soundings to {{convert|10994|m|fathom ft m|order=out}} have since been found near the site of the ''Challenger''{{'}}s original sounding.<ref>{{cite news|last= Amos|first= Jonathan|title= Oceans' deepest depth re-measured|url= https://www.bbc.co.uk/news/science-environment-15845550|date= 7 December 2011|work= BBC News|access-date= 7 December 2011|archive-date= 25 May 2012|archive-url= https://archive.today/20120525110128/http://www.bbc.co.uk/news/science-environment-15845550|url-status= live}}</ref> ''Challenger''{{'}}s discovery of this depth was a key finding of the expedition in broadening oceanographic knowledge about the ocean's depth and extent; the depression, the [[Challenger Deep]], now bears the name of the vessel and its successor, [[HMS Challenger (1931)|HMS ''Challenger'' II]], which in 1951 identified a depth of 5,944 fathoms nearby.<ref>{{Cite news|url=http://www.gebco.net/data_and_products/undersea_feature_names/#feature_links4|title=IHO-IOC GEBCO Gazetteer of Undersea Feature Names|date=August 2011|publisher=GEBCO|access-date=20 March 2012|archive-date=14 March 2012|archive-url=https://web.archive.org/web/20120314233143/http://www.gebco.net/data_and_products/undersea_feature_names/#feature_links4|url-status=live}}</ref> [[Tom Gaskell|Thomas Gaskell]], the Chief Scientist on HMS ''Challenger'' II, observed that the later measurement<blockquote>was not more than 50 miles from the spot where the nineteenth-century ''Challenger'' found her deepest depth [...] and it may be thought fitting that a ship with the name ''Challenger'' should put the seal on the work of that great pioneering expedition of oceanography.<ref>{{Cite book |last=Gaskell |first=Thomas |title=Under the Deep Oceans: Twentieth Century Voyages of Discovery |publisher=Eyre & Spottiswoode |year=1960 |location=London |pages=24–25}}</ref></blockquote>The expedition also verified the existence of the Mid-Atlantic Ridge extending from the southern hemisphere to the northern one.<ref name="Aitken_t1" />