Editing Challenger Deep (section)

===1959 – RV ''Stranger''===
The first definitive verification of both the depth and location of the Challenger Deep (western basin) was determined by Dr. R. L. Fisher from the [[Scripps Institution of Oceanography]], aboard the 325-ton research vessel ''Stranger''. Using explosive soundings, they recorded {{convert|10850|±|20|m|ft|0|abbr=on}} at/near {{Coord|11|18|N|142|14|E}} in July 1959. ''Stranger'' used celestial and [[LORAN-C]] for navigation.<ref>{{cite web |date= |title=Challenger Deep |url=https://www.ngdc.noaa.gov/gazetteer/ |publisher=[[NOAA]] |access-date=6 November 2019 |archive-date=23 April 2021 |archive-url=https://web.archive.org/web/20210423032853/https://www.ngdc.noaa.gov/gazetteer/ |url-status=live }}</ref><ref>Fisher, R. L., and H. H. Hess, "Trenches", in ''The Earth Beneath the Sea'', vol. 3, pp. 411–436, Table 1, 1963</ref> LORAN-C navigation provided geographical accuracy of {{convert|460|m|ft|0|abbr=on}} or better.<ref>Floyd, P. A., ''Ocean Basalts'', Springer, 1991, p. 12</ref> According to another source RV ''Stranger'' using bomb-sounding surveyed a maximum depth of {{convert|10915|±|10|m|ft|0|abbr=on}} at {{Coord|11|20.0|N|142|11.8|E}}.<ref name="Bathymetric mapping of the world's deepest seafloor, Challenger Deep"/> Discrepancies between the geographical location (lat/long) of ''Stranger''{{'s}} deepest depths and those from earlier expeditions (''Challenger II'' 1951; ''Vityaz'' 1957 and 1958) "are probably due to uncertainties in fixing the ships' positions".<ref name="Fisher, Trenches p. 416">Fisher, "Trenches", ''The Earth Beneath the Sea'', p. 416, 1963</ref> ''Stranger''{{'s}} north-south zig-zag survey passed well to the east of the eastern basin southbound, and well to the west of the eastern basin northbound, thus failed to discover the eastern basin of the Challenger Deep.<ref>Fisher, "Trenches", ''The Earth Beneath the Sea'', p. 417, Fig. 2, 1963</ref> The maximum depth measured near longitude 142°30'E was {{convert|10760|±|20|m|ft|0|abbr=on}}, about 10&nbsp;km west of the eastern basin's deepest point. This was an important gap in information, as the eastern basin was later reported as deeper than the other two basins.
''Stranger'' crossed the center basin twice, measuring a maximum depth of {{convert|10830|±|20|m|ft|0|abbr=on}} in the vicinity of 142°22'E. At the western end of the central basin (approximately 142°18'E), they recorded a depth of {{convert|10805|±|20|m|ft|0|abbr=on}}.<ref name="jproc.ca">{{cite web |url=http://www.jproc.ca/hyperbolic/loran_c.html |title=Loran-C Introduction |website=Hyperbolic Radionavigation Systems |access-date=6 November 2019 |archive-date=10 June 2021 |archive-url=https://web.archive.org/web/20210610004404/http://jproc.ca/hyperbolic/loran_c.html |url-status=live }}</ref>{{failed verification|date=January 2020}}
The western basin received four [[transects]] by ''Stranger'', recording depths of {{convert|10830|±|20|m|ft|0|abbr=on}} toward the central basin, near where ''Trieste'' dived in 1960 (vicinity {{Coord|11|18.5|N|142|15.5|E}}, and where ''Challenger II'', in 1950, recorded {{convert|10863|±|35|m|ft|0|abbr=on}}. At the far western end of the ''western'' basin (about 142°11'E), the ''Stranger'' recorded {{convert|10850|±|20|m|ft|0|abbr=on}}, some 6&nbsp;km south of the location where ''Vityaz'' recorded {{convert|11034|±|50|m|ft|0|abbr=on}} in 1957–1958. Fisher stated: "differences in the ''Vitiaz'' [sic] and ''Stranger''–''Challenger II'' depths can be attributed to the [sound] velocity correction function used".<ref name="Fisher, Trenches p. 416"/> 
After investigating the Challenger Deep, ''Stranger'' proceeded to the [[Philippine Trench]] and transected the trench over twenty times in August 1959, finding a maximum depth of {{convert|10030|±|10|m|ft|0|abbr=on}}, and thus established that the Challenger Deep was about {{convert|800|m|ft}} deeper than the Philippine Trench.<ref>Fisher, "Trenches", ''The Earth Beneath the Sea'', Table I, p 418</ref> The 1959 ''Stranger'' surveys of the Challenger Deep and of the Philippine Trench informed the U.S. Navy as to the appropriate site for ''Trieste''{{'s}} record dive in 1960.<ref>{{cite magazine |last1=Fisher |first1=Robert L. |year=2009 |title=Meanwhile, Back on the Surface |url=https://www.globaloceandesign.com/uploads/3/0/7/4/30747513/2009_into_the_trench_part_1.pdf |magazine=Marine Technology Society Journal |language=en |publisher=[[Marine Technology Society]] |volume=43 |issue=5 |pages=16–19 |issn=0025-3324 |archive-url=https://web.archive.org/web/20230416014230/https://www.globaloceandesign.com/uploads/3/0/7/4/30747513/2009_into_the_trench_part_1.pdf |archive-date=2023-04-16 |access-date=2024-01-12 }}</ref>