U 400 (POSSIBLY) - Cornwall & Devon

Now this one, for us, is pure speculation and that’s what makes it so damn interesting. The U-400, a Type VIIC U-boat, went down off the Cornish coast in December 1944. Officially, it was mined, but finding the wreck has proven… elusive. We’re talking about diving to 56 metres here, a serious technical dive, often in challenging conditions. When you drop down onto *this* wreck – if it truly is the U-400 – the feeling of history is palpable. The darkness, the cold, the sheer depth – it all adds to the atmosphere. The wreck itself lies on a silty seabed, usually upright but often partially buried. It's a proper submarine shape, recognisable even with the years of growth. We’ve found the conning tower often intact, draped in fishing nets and anemones, with shoals of bib darting through the periscope shears. Heading along the deck, you’ll spot sections of the casing starting to peel away, revealing the pressure hull beneath. It’s a somber, industrial landscape down there, colonised by the sea. Think big conger eels lurking in torpedo tubes, spider crabs scuttling over the hull, and dense clouds of plumose anemones blooming from every crevice. Visibility can be hit or miss, but when it's good, seeing that long, grey silhouette emerge from the gloom is genuinely special. It suits experienced wreck divers who appreciate the hunt as much as the dive itself, and who are properly kitted out for deep, cold water.

Location
Cornwall & Devon, United Kingdom, Mediterranean & Europe
Coordinates
50.523350, -5.381017
Type
wreck
Maximum Depth
56m

Marine Protected Area: Kelsey Head

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 U 400 (POSSIBLY)

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 U 400 (POSSIBLY)

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