SM UC-8 was a German Type UC I minelayer submarine or U-boat in the German Imperial Navy () during World War I. The U-boat had been ordered by November 1914 and was launched on 6 July 1915. She was commissioned into the German Imperial Navy on 5 July 1915 as SM UC-8. Mines laid by UC-8 in her one patrol are not known to have sunk any ships. UC-8 ran aground on the Dutch coast near Terschelling on 4 November 1915. Interned by the Dutch, UC-8 was purchased and commissioned into the Dutch Navy as HNLMS M 1. The submarine was broken up in 1932.
A Type UC I submarine, UC-8 had a displacement of when at the surface and while submerged. She had a length overall of , a beam of , and a draught of . The submarine was powered by one Daimler-Motoren-Gesellschaft six-cylinder, four-stroke diesel engine producing , an electric motor producing , and one propeller shaft. She was capable of operating at a depth of .
The submarine had a maximum surface speed of and a maximum submerged speed of . When submerged, she could operate for at ; when surfaced, she could travel at . UC-8 was fitted with six mine tubes, twelve UC 120 mines, and one machine gun. She was built by AG Vulcan Stettin and her complement was fourteen crew members.