| Navy | The Royal Navy |
| Type | Submarine |
| Class | Porpoise |
| Pennant | N 83 |
| Built by | Scotts Shipbuilding & Engineering Co. (Greenock, Scotland) |
| Ordered | |
| Laid down | 12 May, 1936 |
| Launched | 2 Dec, 1937 |
| Commissioned | 15 Aug, 1938 |
| Lost | 30 Jul, 1941 |
| Loss position | 32.49N, 20.11E (See a map) |
| History | HMS Cachalot (Lt. Hugo Rowland Barnwell Newton, DSO, RN) was rammed and sunk about 45 nautical miles north of Benghazi, Libya in position 32º49'N, 20º11'E by the Italian torpedo boat Generale Achille Papa. Cachalot was attacking the Italian merchant Capo Orso (3149 GRT) with gunfire when she was rammed and sunk by it's escort.
Commanding Officers: Lt.Cdr. John David Luce, RN Lt. Hugo Rowland Barnwell Newton, DSC, RN |
| Noteable events involving Cachalot include: 19 Aug, 1940 20 Aug, 1940 23 Sep, 1940 24 Sep, 1940 26 Jan, 1941 15 Feb, 1941 The same day she also makes a torpedo attack on a merchant ship but without result. |

