SM UB-90 was a German Type UB III submarine or U-boat in the German Imperial Navy (German: Kaiserliche Marine) during World War I. She was commissioned into the German Imperial Navy on 21 March 1918 as SM UB-90.
On 16 October 1918, UB-90 was hit by a torpedo from at 57.9167°N 37°W and sunk. All 38 crew members died in the event.
See main article: Type UB III submarine. She was built by AG Vulcan of Hamburg and following just under a year of construction, launched at Hamburg on 12 February 1918. UB-90 was commissioned early the next year under the command of Oblt.z.S. Gottfried von Mayer. Like all Type UB III submarines, UB-90 carried 10 torpedoes and was armed with a 10.52NaN2 deck gun. UB-90 would carry a crew of up to 3 officer and 31 men and had a cruising range of 7120nmi. UB-90 had a displacement of 510lk=inNaNlk=in while surfaced and 640t when submerged. Her engines enabled her to travel at 13kn when surfaced and when submerged.
| Date | Name | Nationality | Tonnage[1] | Fate[2] | |
|---|---|---|---|---|---|
| 29 July 1918 | Douro |  Denmark | 850 | Captured as prize | |
| 3 October 1918 | Eupion |  United Kingdom | 3,575 | Sunk |