Editing Challenger Deep (section)

===2015 – USCGC ''Sequoia''===
[[File:USCGC Sequoia (WLB-215).jpg|thumb|US Coast Guard Cutter ''Sequoia'' (WLB 215)]]
From 10 to 13 July 2015, the Guam-based 1,930-ton US Coast Guard Cutter [[USCGC Sequoia (WLB-215)|''Sequoia'' (WLB 215)]] hosted a team of researchers, under chief scientist Robert P. Dziak, from the NOAA [[Pacific Marine Environmental Laboratory]] (PMEL), the [[University of Washington]], and Oregon State University, in deploying PMEL's "Full-Ocean Depth Mooring", a 45-meter-long moored deep-ocean [[hydrophone]] and pressure [[sensor array]] into the western basin of the Challenger Deep. A 6-hour descent into the western basin anchored the array at {{convert|10854.7|±|8.9|m|ft|0|abbr=on}} of water depth, at {{Coord|11|20.127|N|142|12.0233|E}}, about 1&nbsp;km northeast of ''Sumner''{{'s}} deepest depth, recorded in 2010.<ref>{{cite web |url=https://www.pmel.noaa.gov/acoustics/featured-publication/noaa-brings-back-first-recordings-deepest-part-ocean |last=Dziak |first=R. P. |display-authors=et al. |title=NOAA brings back first recordings from the deepest part of the ocean |date=16 May 2017 |access-date=22 December 2019 |archive-date=22 December 2019 |archive-url=https://web.archive.org/web/20191222160651/https://www.pmel.noaa.gov/acoustics/featured-publication/noaa-brings-back-first-recordings-deepest-part-ocean |url-status=live }}</ref> After 16 weeks, the moored array was recovered on 2–4 November 2015. "Observed sound sources included earthquake signals (T phases), baleen and odontocete cetacean vocalizations, ship propeller sounds, airguns, active sonar and the passing of a Category 4 typhoon." The science team described their results as "the first multiday, broadband record of ambient sound at Challenger Deep, as well as only the fifth direct depth measurement".<ref>{{cite journal |url=https://www.tos.org/oceanography/assets/docs/30-2_dziak.pdf |last=Dziak |first=Robert P. |display-authors=etal |title=Ambient Sound at Challenger Deep, Mariana Trench |journal=Oceanography |volume=30 |issue=2 |date=June 2017 |doi=10.5670/oceanog.2017.240 |bibcode=2017Ocgpy..30b.240D |access-date=22 December 2019 |archive-date=26 September 2020 |archive-url=https://web.archive.org/web/20200926113553/https://www.tos.org/oceanography/assets/docs/30-2_dziak.pdf |url-status=live }}</ref>