Also known as: M2, HMS M2 submarine
There is truly nothing else like HMS M2 anywhere in the world. Originally completed in 1919 as a submarine monitor carrying a massive 12-inch gun, she was converted in 1927 into the world's first undersea aircraft carrier, fitted with a watertight hangar and catapult for a tiny Parnall Peto floatplane. On 26 January 1932, during a routine exercise off Portland, water flooded through the hangar and she went down with all 60 hands. The salvage investigation found those hangar doors standing open — a haunting detail that has fuelled debate ever since. She rests upright and intact at around 33 metres in Lyme Bay, her 90-metre hull still unmistakably that of a submarine, the cylindrical hangar forward of the conning tower instantly recognisable. As a designated war grave she demands the utmost respect, but for those qualified to make the dive, she offers a genuinely unique encounter with a one-of-a-kind vessel.
Flooded through the aircraft hangar during a training exercise in West Bay, Dorset. The hangar doors were found open during the subsequent salvage investigation. The world's first undersea aircraft carrier — originally armed with a 12-inch gun, later converted to carry a Parnall Peto seaplane launched by catapult and recovered by crane. Entire crew of 60 killed.
HMS M2 is a submarine wreck located off Dorset, United Kingdom at a depth of 35 metres. The vessel was lost due to flooding in 1932. The wreck is diveable.
HMS M2 lies at 31 to 35 metres depth, Approximately 5 miles NW of Portland Bill, Lyme Bay, Dorset.
HMS M2 was lost due to flooding on 26 January 1932, off Dorset, United Kingdom. 60 people lost their lives.
Diving the HMS M2 is rated advanced and is requires an Advanced Open Water certification with wreck diving experience. Minimum certification: PADI Deep Diver or equivalent. Recommended: PADI Deep Diver / BSAC Dive Leader.
The best months to dive HMS M2 are April, May, June, July, August, September, October. Water temperature ranges from 7°C in winter to 18°C in summer.
HMS M2 is accessed by boat from Portland, Dorset, United Kingdom. The wreck is a designated war grave.
| Month | Temp | Visibility | Access | Marine life |
|---|---|---|---|---|
| Jan | 7.0°C | 4.0m | poor | Minimal — winter conditions |
| Feb | 7.5°C | 4.0m | poor | Minimal — winter conditions |
| Mar | 8.0°C | 5.0m | marginal | Minimal — winter conditions |
| Apr | 9.5°C | 6.0m | good | Moderate — season starting |
| May | 11.0°C | 8.0m | good | Good — cuttlefish, wrasse, pollack, nudibranchs |
| Jun | 13.5°C | 12.0m | good | Good — cuttlefish, wrasse, pollack, nudibranchs |
| Jul | 16.0°C | 16.0m | good | Peak — cuttlefish, large shoals, conger eels, nudibranchs, bass |
| Aug | 18.0°C | 20.0m | good | Peak — cuttlefish, large shoals, conger eels, nudibranchs, bass |
| Sep | 17.0°C | 15.0m | good | Good — cuttlefish, wrasse, pollack, nudibranchs |
| Oct | 14.0°C | 8.0m | good | Good — wrasse, pollack |
| Nov | 10.5°C | 6.0m | marginal | Minimal — winter conditions |
| Dec | 8.5°C | 4.0m | poor | Minimal — winter conditions |
3 evidence records from 3 sources.
Submarine aircraft carrier. Flooded through aircraft hangar during training exercise, 26 January 1932. All 60 crew killed. Hangar doors found open.
Designated war grave under Military Remains Act 1986. Depth 31-35m. ~5 miles NW of Portland Bill.
90m long, still in one piece, sits upright on seabed. Bows pointing NNE. World's first undersea aircraft carrier.
Approximately 5 miles NW of Portland Bill, Lyme Bay, Dorset