| SUBVERSION | Removal of stability of model of underwater craft? |
| SUBMACHINEGUN | Could it be part of the armament of underwater craft? (3-7,3) |
| SUBSECTION | One of the parts of an underwater craft? (10) |
| SUBORDER | Group command to underwater craft? (8) |
| SUBCONTRACT | Agreement you sign when you order your new underwater craft? |
| SUBCONTRACTOR | One who agrees to build underwater craft? (13) |
| SUBMISSIVE | Letter for an underwater craft? |
| APLOMB | Stability of a piece of fruit, one might say |
| POISE | Word for weight that came to mean balance, equal weight or equilibrium, thus composure, dignity, graceful carriage, stability of body or other state/manner of evenness (5) |
| UPSET | Disturb the balance or stability of (5) |
| MENTALBALANCE | Stability of mind (6,7) |
| FIRMNESS | Stability of business overlooking loch (8) |
| UPSETS | Disturbs the balance or stability of, by an unexpected victory? (6) |
| SECURITYRISK | Person who threatens the stability of a state (8,4) |
| ROCKS | Lacks the stability of diamonds? (5) |
| EROSION | This has an adverse effect on the stability of the banks (7) |
| CORALREEF | Type of underwater ecosystem home to some 4,000 species of fish, seahorses, sponges, anemones, jellyfish, sea turtles, snappers and starfish (5,4) |
| JACUZZI | A bath with a system of underwater jets to massage the body (7) |
| FISHEYELENS | Wider view apparently offered by this part of underwater camera? |
| EXERT | Use final bits of underwater equipment beneath river |
