HMS B2 was a Royal Navy B class submarine, built at Vickers, Barrow-in-Furness, launched on 30 October 1905 and completed on 9 December 1905. B2 was lost when she accidentally collided with SS Amerika northeast of Dover in the early hours of 4 October 1912. She was commanded by Lieutenant P.B. O’Brien, and was one of several submarines sent to Dover to take part in Channel exercises during the extended lead up to the First World War. B2 was surfaced and was struck just forward of the conning tower. The accident resulted in the deaths of 15 crew members. The only survivor was the boat's bridge officer, Lt. Pulleyne. The boat was not recovered in order to allow the bodies to remain undisturbed. In recent years the wreck was discovered by amateur divers.