Some of the earliest explorations of the trench occurred in the late 1950s when Robert L. Fisher, a research geologist at the
Scripps Institution of Oceanography, investigated the trench as part of a worldwide scientific field exploration of the world's ocean floor and sub-oceanic crustal structure. Bomb-sounding, echo-train analysis, and manometer were some of the techniques used to determine the depth of the trench. The research contributed to an understanding of the subduction characteristic of the Pacific margins. Various agencies have explored the trench in the aftermath of the 2004 earthquake, and these explorations have revealed extensive changes in the ocean floor.
Crewed descent and DSV Limiting Factor'' at its stern On 5 April 2019
Victor Vescovo made the first crewed descent to the deepest point of the trench in the Deep-Submergence Vehicle
Limiting Factor (a Triton 36000/2 model submersible) and measured a depth of ± by direct
CTD pressure measurements at 11°7'44" S, 114°56'30" E, about south of
Bali. The operating area was surveyed by the support ship, the Deep Submersible Support Vessel
DSSV Pressure Drop, with a Kongsberg SIMRAD EM124 multibeam echosounder system. The gathered data was donated to the
GEBCO Seabed 2030 initiative. The dive was part of the Five Deeps Expedition. The objective of this expedition is to thoroughly map and visit the deepest points of all five of the world's oceans by the end of September 2019. To resolve the debate regarding the deepest point of the Indian Ocean, the
Diamantina fracture zone was surveyed by the Five Deeps Expedition in March 2019, recording a maximum water depth of ± at 33°37'52" S, 101°21'14" E for the
Dordrecht Deep. == Associated seismicity ==