| Navy | The Royal Navy |
| Type | Submarine |
| Class | U |
| Pennant | N 48 |
| Built by | Vickers Armstrong (Barrow-in-Furness, U.K.) |
| Ordered | |
| Laid down | 19 Feb, 1937 |
| Launched | 5 Oct, 1937 |
| Commissioned | 21 Aug, 1938 |
| Lost | 7 Jan, 1940 |
| Loss position | |
| History | While on her fourth war patrol (departed Blyth on 31 December 1939) HMS Undine (Lt.Cdr. Alan Spencer Jackson, RN) at 0940 hours on 7 January sighted what was thought to be three trawlers 20 miles south west of Heligoland but these were in fact the German auxiliary minesweepers M-1201, M-1204 and M-1207. Undine unsuccessfully attacked the leading vessel but after some 5 minutes an explosion shook the submarine, blowing her upwards and rendering the hydroplanes useless. Without the use of the hydroplanes escape would have been impossible and the order to abandon ship was give. Demolition charges were set and the submarine scuttled. The crew entered the water and were picked up by the minesweepers.
Commanding Officer: |

