SM U-104 was a German Type U 57 U-boat during the First World War. U-104 was built at AG Weser in Bremen, launched on 3 July 1917 and commissioned on 12 August 1917. She completed four patrols under Kptlt. Kurt Bernis and was responsible for the sinking of nine vessels of a total of .[1]
On 25 April 1918 the U-104 was engaged by in St. George's Channel and severely damaged. Later the same day came upon her and dropped further depth-charges, sinking her and leaving but a single survivor of her 42-member crew. The wreckage lies at position 51.9833°N -32°W.
| Date | Name | Nationality | Tonnage[2] | Fate[3] | |
|---|---|---|---|---|---|
| 26 October 1917 | Sapele |  United Kingdom | 4,366 | Sunk | |
| 15 December 1917 | Maidag |  Norway | 1,253 | Sunk | |
| 21 December 1917 | Spro | Norway | 1,507 | Sunk | |
| 25 December 1917 | Ajax |  Denmark | 1,018 | Sunk | |
| 2 March 1918 | Kenmare | United Kingdom | 1,330 | Sunk | |
| 12 April 1918 | Njaal | 578 | Sunk | ||
| 16 April 1918 | Widwud | 299 | Sunk | ||
| 20 April 1918 | Lowther Range | United Kingdom | 3,926 | Sunk | |
| 22 April 1918 | Fern | United Kingdom | 444 | Sunk |