SM UC-70 was a German Type UC II minelaying submarine or U-boat in the German Imperial Navy () during World War I. The U-boat was ordered on 12 January 1916 and was launched on 7 August 1916. She was commissioned into the German Imperial Navy on 20 November 1916 as SM UC-70. In ten patrols UC-70 was credited with sinking 33 ships, either by torpedo or by mines laid. On 28 August 1918, UC-70 was spotted lying submerged on the sea bottom and attacked by a Blackburn Kangaroo patrol aircraft of No. 246 Squadron RAF and then was then sunk by depth charges from the British destroyer . The wreck is a Protected Wreck managed by Historic England.
A Type UC II submarine, UC-70 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 two six-cylinder four-stroke diesel engines each producing (a total of ), two electric motors producing , and two propeller shafts. She had a dive time of 48 seconds and was capable of operating at a depth of .
The submarine had a maximum surface speed of and a submerged speed of . When submerged, she could operate for at ; when surfaced, she could travel at . UC-70 was fitted with six mine tubes, eighteen UC 200 mines, three torpedo tubes (one on the stern and two on the bow), seven torpedoes, and one Uk L/30 deck gun. Her complement was twenty-six crew members.
UC-70 was depth charged and sunk off Whitby, Yorkshire on 28 August 1918 with the loss of all 31 crew. The wreck was given protected status by Historic England in 2017.