Sunda Trench an underwater ridge, and much of the trench is at least partially filled with sediments. Mappings after the 2004 Indian Ocean earthquake of the plate boundary showed resemblance to suspension bridge cables, with peaks and sags, indicative of asperity and locked faults, instead of the traditional wedge shape expected. Some of the earliest exploration of the Trench occurred in the late 1950s when Robert Fisher, 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
Romanche Trench the French navy ship "La Romanche", commanded by captain Louis-Ferdinand Martial which on 11 October 1883 made soundings that revealed the trench. The boat was coming to France after a few months scientific mission near cape Horn, part of the first International Polar Year. The trench has a depth of , is long and has an average width of and allows for a major circulation of deep ocean basin water from the west Atlantic to the east Atlantic basins. Deep water flow through the trench is from west to east with a rate of 3.6 Sverdrups (million m³/s) of water.