SM UB-25 was a German Type UB II submarine or U-boat in the German Imperial Navy (German: Kaiserliche Marine) during World War I. The U-boat was ordered on 30 April 1915 and launched on 9 October 1915. She was commissioned into the German Imperial Navy on 11 December 1915 as SM UB-25. The submarine was lost in a collision with SMS V26 in Kiel harbour on 17 March 1917. She was raised on 22 March 1917 by the salvage ship and served on as a training boat until surrendered to the Allies at Harwich on 26 November 1918 in accordance with the requirements of the Armistice with Germany. She was sold by the British Admiralty to George Cohen on 3 March 1919 for £750 (excluding her engines), and was broken up at Canning Town.