SM UC-51 was a German Type UC II minelaying submarine or U-boat in the German Imperial Navy (German: Kaiserliche Marine) during World War I. The U-boat was ordered on 20 November 1915 and was launched on 5 December 1916. She was commissioned into the German Imperial Navy on 6 January 1917 as SM UC-51. In seven patrols UC-51 was credited with sinking 28 ships, either by torpedo or by mines laid. UC-51 was mined and sunk in the English Channel on 17 November 1917. The wreck was located and identified by marine archaeologist Innes McCartney close to the official sinking position in 2001.