SM UB-118 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 January 1918 as SM UB-118. UB-118 was surrendered to the Allies at Harwich on 21 November 1918 in accordance with the requirements of the Armistice with Germany. She was allocated to British explosive trials at Falmouth (see UB-86, UB-97, UC-92, UB-106, UB-112 and UB-128), but began to take water while in tow from Devonport to Falmouth, and was therefore sunk by her escort on 21 November 1920.