HMS C11 was a British C-class submarine built by Vickers, Barrow. She was laid down on 6 April 1906 and was commissioned on 3 September 1907. C11 was sunk in a collision with the collier Eddystone in the North Sea south of Cromer, Norfolk on the 14 July 1909. There were only three survivors. The wreck was discovered in the late 1990s.