SM UB-81 was a German Type UB III submarine or U-boat in the German Imperial Navy () during World War I. She was commissioned into the German Imperial Navy on 18 September 1917 as SM UB-81. UB-81 was sunk 2 December 1917 by a mine at , 29 crew members died in the event.
| Identifier (URI) | Rank |
|---|---|
| dbkwik:resource/g9-thWFk7mMhqw5gOIT9xA== | 5.88129e-14 |
| dbr:SM_UB-81 | 5.88129e-14 |