The bulk modulus is affected by temperature, pressure, and dissolved impurities (usually salinity). The speed is determined by the water's bulk modulus, mass, and density. Further, sonar operation is affected by variations in sound speed, particularly in the vertical plane. This is especially important when sounding in deep water, as the resulting footprint of an acoustic pulse gets large once it reaches a distant sea floor. The accuracy of determining geographical location, and the beamwidth of (multibeam) echosounder systems, limits the horizontal and vertical bathymetric sensor resolution that hydrographers can obtain from onsite data. Over many years, the search for, and investigation of, the location of the maximum depth of the world's oceans has involved many different vessels, and continues into the twenty-first century. Please discuss this issue on the talk page and edit it to conform with Wikipedia's Manual of Style by replacing the section with a link and a summary of the repeated material or by spinning off the repeated text into an article in its own right. This section duplicates the scope of other sections, specifically #Descents. This conforms with the description of Challenger Deep as consisting of an elongated seabed section with distinct sub-basins or sediment-filled pools. ĭetailed sonar mapping of the western, center and eastern basins in June 2020 by the DSSV Pressure Drop combined with crewed descents revealed that they undulate with slopes and piles of rocks above a bed of pelagic ooze. The closest land to the Challenger Deep is Fais Island (one of the outer islands of Yap), 287 km (178 mi) southwest, and Guam, 304 km (189 mi) to the northeast. Both the western and eastern basins have recorded depths (by sonar bathymetry) in excess of 10,920 m (35,827 ft), while the center basin is slightly less deep. The three basins feature extends about 48 km (30 mi) west to east if measured at the 10,650 m (34,941 ft) isobath. The Challenger Deep consists of three basins, each 6 to 10 km (3.7 to 6.2 mi) long, 2 km (1.2 mi) wide, and over 10,850 m (35,597 ft) in depth, oriented in echelon from west to east, separated by mounds between the basins 200 to 300 m (660 to 980 ft) higher. The Challenger Deep is a relatively small slot-shaped depression in the bottom of a considerably larger crescent-shaped oceanic trench, which itself is an unusually deep feature in the ocean floor. Topography Sonar mapping of the Challenger Deep by the DSSV Pressure Drop employing a Kongsberg SIMRAD EM124 multibeam echosounder system (26 April – ) As of July 2022, twenty-seven people have descended to Challenger Deep. During the third Ring of Fire Expedition in the summer of 2022, the DSV Limiting Factor made an additional nine descents to the Challenger Deep. Between 1 March and 13 April 2021, the DSV Limiting Factor's second Ring of Fire Expedition added five completed dives. The deep-sea submersible Fendouzhe (奋斗者, Striver) completed a crewed dive to the bottom of the Challenger Deep on 10 November 2020 with three scientists onboard whilst livestreaming the descent. Between 6 June and 26 June 2020, the DSV Limiting Factor added six completed dives during the first Ring of Fire Expedition. Between 28 April and, the DSV Limiting Factor led by Victor Vescovo completed four crewed dives to the bottom of Challenger Deep. In March 2012, a solo descent was made by film director James Cameron in the deep-submergence vehicle Deepsea Challenger. During the next 50 years, 3 unpiloted visits were launched in 1996, 19. The first descent by any vehicle was by Jacques Piccard and Don Walsh in the bathyscaphe Trieste in January 1960. The high water pressure at this depth makes designing and operating exploratory craft difficult. The depression is named after the British Royal Navy survey ship HMS Challenger, whose expedition of 1872–1876 made the first recordings of its depth. This location is in the ocean territory of the Federated States of Micronesia. The Challenger Deep is located in the western Pacific Ocean, at the southern end of the Mariana Trench, near the Mariana Islands. Its depth is measured at 10,902–10,929 m (35,768–35,856 ft) by direct measurement from deep-diving submersibles, remotely operated underwater vehicles and benthic landers, and (sometimes) slightly more by sonar bathymetry. The Challenger Deep is the deepest known point of the seabed of Earth. Location of Challenger Deep within the Mariana Trench and western Pacific Ocean
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