HMS M2 was one of three monitor submarines, launched at the end of the First World War 1918 and later converted into an aircraft carrying submarine in 1927 and foundered on exercise on 26th January 1932.
She was built by Vickers Ship Builders (Now BAE) in Barrow in Furness. The keel was laid in 1916 and the M-class were designed to replace the ill-fated K-class.
HMS M2 was 295ft long, 24ft wide and displaced 1,977 tons when submerged and 1,620 tons on the surface. She was powered by two 12 cylinder 1,800 Kw Vickers diesel engines, powering four 2,400 Kw electric motors which worked together to turn the two shafts, each fitted with a three-bladed propellor.
On the surface, she had a top speed of 15 knots and 9 knots when submerged and had a range of up to 4,500, when steaming economically.
She had a complement of 62 officers and men and was armed initially with a single fixed 12” Mk IX gun, (which were storob’d from the Formidable-class), a 3” anti-aircraft gun and four 18” torpedo tubes. Following the accidental sinking of sister ship M1 in 1925, M2 was refitted. The 12” gun was removed and replaced with a hangar and a hydraulic catapult, housing a Parnell Peto Seaplane.
On 26 January 1932, HMS M2 left her base at Portland, for an exercise in West Bay, Dorset. Her last communication was a message to her submarine depot ship, announcing her intention to dive at 10:30. The captain of Tynesider, a passing merchant ship, , mentioned that he had seen a large submarine dive stern first at around 11:15. Unaware of the significance, this was only reported once he reached port.
Her entire crew was killed in the accident. She was found on 3 February, eight days after her loss. In a salvage operation lasting nearly a year and 1,500 dives, on 8 December 1932, she was lifted to within 20 ft of the surface before a gale sprang up, sending her down to her final resting place.
The hangar door was later found to be open and the aircraft still housed within it. The accident was believed to be due to water ingress through the hangar door, which had been opened to launch the aircraft shortly after surfacing.
The submarine currently lies upright on the sea bed at (50°34.6′N 2°33.93′W). Her keel is about 100 ft (30 m) below the surface at low tide, and her highest point at the top of the conning tower at around 66 ft (20 m). She is a popular dive for scuba divers. The wreck is designated as a "protected place" under the Protection of Military Remains Act 1986.
After the loss of HMS M2, the Royal Navy abandoned submarine-launched aircraft.
