The M2 is classified as a war grave due to the fact that she sank as the result of an accident in 1932 killing all the crew. This submarine was unique in that she carried a small aircraft in a hanger built on to the conning tower and it is thought that whilst practising emergency diving the hangar door was not properly closed, quickly flooding the ship and sending her to the bottom. She is an amazing dive virtually intact apart from the crane for aircraft recovery having been trawled off a few years ago and some clandestine salvage, which saw the removal of her propellers.
