JMT M99 - Cornwall & Devon

The JMT M99, a fishing vessel resting at 51 metres, is a proper technical dive, and one we absolutely love in the often-overlooked waters of Cornwall. This isn't a beginner’s drift, the depth means you’ll need your certs and your wits about you, but the rewards are there. We often find the visibility here surprisingly good for the UK, sometimes pushing 15 metres on a calm day, allowing the wreck to emerge slowly from the green depths. What makes the M99 so special? It’s not just a pile of metal; it’s still very much a ship. You can make out the wheelhouse, the hold, and the deck machinery, all encrusted with dense plumose anemones that pulse gently in the current. We’ve often seen conger eels lurking in the deeper recesses, and large pollack drift lazily above the superstructure. It’s a site that feels remote and wild, a true expedition into the cool, dark Atlantic. Our best advice? Pick a slack tide, pack an extra cylinder, and take your time exploring her.

Location
Cornwall & Devon, United Kingdom, Mediterranean & Europe
Coordinates
50.261850, -4.285900
Type
wreck
Maximum Depth
51m

Marine Protected Area: Rame 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 JMT M99

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 JMT M99

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