SM U-87 was one of the 329 submarines serving in the Imperial German Navy (Kaiserliche Marine) in World War I.U-87 was engaged in the naval warfare and took part in the First Battle of the Atlantic. She sank some 22 merchant vessels before 25 December 1917, when rammed U-87 in the Irish Sea and depth-charged her. Then the P-class sloop sank her. U-87's entire crew of 44 were lost.