SM U-5 was a German Type U 5 U-boat built for the Kaiserliche Marine. She was commissioned 2 July 1910 in Germaniawerft in Kiel. She served in World War I under the command of Johannes Lemmer, with no recorded sinkings of enemy ships on two patrols. She was lost in an accident off the Belgian coast 18 December 1914, with all hands lost.