| MARIANA | Trench that's the deepest place in the ocean |
| TRENCH | Mariana ___, the deepest place on Earth. |
| BERMUDATRIANGLE | Urgent, Admiral, be prepared for a maybe dangerous place in the ocean (7,8) |
| MARIANAS | ___ Trench, deepest place in the 10-Down |
| THREAD | Walk around end of trench that's needed for sewer (6) |
| CHALLENGER | - Deep; situated around 11km below sea level in the Mariana Trench, the deepest known point in Earth |
| LOCHMORAR | Situated four miles from Mallaig in the Scottish Highlands, the deepest body of freshwater in the British Isles (4,5) |
| MORAR | With Ben Nevis in its view and home to the legendary Morag, loch which is the deepest freshwater body in the British Isles (5) |
| HELLSCANYON | Cut by the Snake River in Idaho, it is the deepest gorge in the US |
| BAIKAL | Lake ... in Siberia is the deepest in the world (6) |
| TANGANYIKA | Longest freshwater lake in the world and the deepest in Africa (10) |
| WASTWATER | Lake in the Lake District noted as the deepest in England (9) |
| BASS | One of the words for a flax, hemp, jute or lime fibre bag for holding an angler's fish; a powerful sea perch with a brilliant silver body; or, from "low", the lowest part in music or the deepest male |
| OREGON | Crater Lake, the deepest lake in the United States, is in which state? (6) |
| CATSTEVENS | He wrote the Rod Stewart hit "The First Cut Is the Deepest" |
| HADAL | Relating to the deepest parts of the ocean (below 6000 meters) |
| LAKE | Crater ___, the deepest in the U.S. |
| TAHOE | One of the deepest lakes in the U.S. |
| DARK | Like the deepest parts of the ocean |
| OER | "They who know the most must mourn the deepest __ the fatal truth" (Byron) |
