In 1925, the British submarine HMS M1 tragically sank following a collision with the Swedish collier SS Vidar in the English Channel. Resting upright on the seabed off Start Point, Devon, at a depth of 58 metres, this extraordinary wreck is now one of the UK's most revered deep technical dives.
What makes the M1 truly unique is its massive 12-inch gun, mounted forward of the conning tower — a relic from a bygone era of submarine design. The wreck is remarkably intact, with the gun still trained to port and the periscope housing visible amid the encrusting plumose anemones and dead men's fingers.
Due to the depth and strong tidal currents, we strictly limit these expeditions to certified trimix divers. Our expert guides use shot lines and advanced gas planning to ensure you have ample bottom time to explore this historic monument while prioritising safety in the challenging conditions of the Channel.
