part of adjacent to ocean ocean trench FTT:609 TGN:23464 EcoLexicon:deep_sea_trench TGN:23462 Trench FTT:1021 Geonames:U.TRGU SWEETRealm:Trench undersea trench ENVO:00000275 FTT:610 deep deep sea trench https://en.wikipedia.org/wiki/Ocean_trench Hemispheric-scale long but narrow topographic depressions of the sea floor. They are the deepest parts of the ocean floor. Geonames:U.TRNU ENVO ocean floor sea floor trench