HMSM A1 - Cornwall & Devon

Diving the A1 submarine off Selsey is a trip back in time, and one we always recommend for wreck enthusiasts visiting the south coast. This isn't a deep dive, sitting at a maximum of 9m, so it's accessible to a broader range of divers, perfect for those wanting to explore history without pushing depth limits. The A1 was the Royal Navy's first home-built submarine, sunk after a collision in 1904, and you can really feel that history when you’re down there. The wreck itself is largely intact, lying upright on the seabed. You can make out the torpedo tubes at the bow, and there's a distinct shape to the conning tower. We love drifting along the hull, tracing the lines of her design. Schools of small pollack often shelter within the structure, darting in and out, and you'll find plenty of spider crabs making themselves at home amongst the plates. Visibility can vary here, as with many UK sites, but on a good day, the low depth means sunlight penetrates beautifully, illuminating the dark metal and the marine life clinging to it. Our tip? Aim for slack water to really appreciate the details without fighting a current. It’s a genuinely evocative dive, a real piece of naval heritage you can touch.

Location
Cornwall & Devon, United Kingdom, Mediterranean & Europe
Coordinates
50.742416, -0.921317
Type
wreck
Maximum Depth
9m

Marine Protected Area: East Head West Wittering

Best Time to Dive in Cornwall & Devon

The warmest water temperatures in Cornwall & Devon occur in January, averaging 9.6°C. The coolest conditions are in December at 9.6°C.

Monthly Water Temperatures

  • January: 9.6°C (air: 7.3°C)
  • February: 9.6°C (air: 8.4°C)
  • March: 9.6°C (air: 8.6°C)
  • April: 9.6°C (air: 10.1°C)
  • May: 9.6°C (air: 12.6°C)
  • June: 9.6°C (air: 15.2°C)
  • July: 9.6°C (air: 16.6°C)
  • August: 9.6°C (air: 17.1°C)
  • September: 9.6°C (air: 15.9°C)
  • October: 9.6°C (air: 13.5°C)
  • November: 9.6°C (air: 10.7°C)
  • December: 9.6°C (air: 8.7°C)

Nearby Dive Sites in Cornwall & Devon

Nearest Dive Centres to HMSM A1

Marine Life in Cornwall & Devon

Home to 192 recorded species including 93 reef fish, 18 sharks & rays, 13 whales & dolphins, 11 crabs & lobsters, 11 other, 10 seagrass & algae.

Notable Species

Recommended Packing List for HMSM A1

Based on average water temperature of 9.6°C.

  • Drysuit - water at 10°C demands a drysuit with thermal undergarments
  • Hood & Gloves (7mm+) - critical to prevent heat loss
  • Mask - essential for every dive
  • Fins
  • BCD - buoyancy compensator
  • Regulator - your most safety-critical piece of gear
  • Dive Computer - tracks depth, time, and NDL
  • Surface Marker Buoy (SMB) - essential for boat pickups
  • Dive Torch - useful for crevices and colour at depth
  • Underwater Camera - capture your diving memories