SM UB-83 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 15 October 1917 as SM UB-83. UB-83 was sunk on 10 September 1918 by HMS Ophelia off Orkney at 58°28′N 1°50′W / 58.467°N 1.833°W, all 35 of the crew members died in the event.