HMS K7 was a K class submarine built by HM Dockyard, Devonport. She was laid down on 8 November 1915 and commissioned in July 1917. K7 was involved in the accident with the 4th Light Cruiser Squadron. She was also involved in the Battle of May Island exercise. K7 was damaged in the exercise by running over the sinking K4. K7 was sold on 9 September 1921 at Sunderland.