HMSM D1 - Cornwall & Devon

Diving the HMSM D1 is a proper journey back in time, and one we always look forward to when conditions are right. This isn't your average pile of twisted metal; the D1, prototype for the Royal Navy's first diesel subs, lies upright and remarkably intact at 48 metres. You really get a sense of its pioneering design as you follow the hull. We love tracing the outline of the conning tower, imagining the secrecy that surrounded its launch in 1908. The real draw here, beyond the history, is the atmosphere – that deep, silty quiet of a forgotten vessel. Life has well and truly moved in; expect to see conger eels peering from every dark opening, their thick bodies often startling you as you fin past. The deck is often dusted with dead man’s fingers, and we've spotted plenty of inquisitive spider crabs picking their way across the old plating. It’s a dive that demands good deep diving experience and a calm day for the best visibility, which, let’s be honest, can be hit or miss in these parts. But when it's good, it’s exceptionally rewarding for those who appreciate maritime history and the quiet beauty of a deep, historical wreck.

Location
Cornwall & Devon, United Kingdom, Mediterranean & Europe
Coordinates
50.332832, -3.499483
Type
wreck
Maximum Depth
48m

Marine Protected Area: Berry Head to Sharkham Point

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 D1

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 D1

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