What kind of u-boat was the SM U-30

SM U-30 was one of 329 U-boat submarines serving in the Imperial German Navy in World War I. She engaged in commerce warfare as part of the First Battle of the Atlantic. U-30 is significant for the torpedoing of the US tanker Gulflight on 1 May 1915 20 nautical miles (37 km; 23 mi) west of Scilly.