SM U-161 was one of the 329 submarines serving in the Imperial German Navy in World War I. U-161 was engaged in naval warfare and took part in the First Battle of the Atlantic. U-161 was surrendered to the Allies at Harwich on 20 November 1918 in accordance with the requirements of the Armistice with Germany. Having been exhibited at Devonport in December 1918, she was then laid up there until sunk as in the English Channel by gunfire from the submarines L21 and L52 on 30 June 1921 in company with U-135.