SM UB-124 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 22 April 1918 as SM UB-124. UB-124 was sunk on 20 July 1918 by HMS Marne, , Pigeon, and more than 30 patrol craft at 55°43′N 7°51′W / 55.717°N 7.850°W.