SM UB-46 was a Type UB II submarine or U-boat for the German Imperial Navy (German: Kaiserliche Marine) during World War I. UB-46 operated in the Mediterranean and the Black Seas, and was sunk by a mine in December 1916. In early December 1916, during the submarine's fifth patrol, UB-46 struck a mine in the Black Sea a short distance from the north entrance to the Bosphorus and sank with all hands. In her six-month career, UB-46 sank four ships of 8,099 gross register tons (GRT).