Cornwall

The Plymouth Eddystone Rock 22 km south of Plymouth marks the site of the famous Eddystone Lighthouse and its predecessors, and the rocky reef and scattered wreck debris of the 1703 lighthouse sits in 20–36 m of often fast-running but clear water. Bull huss, conger eels, and large velvet swimming crabs inhabit the reef, while plankton-rich tides attract blue sharks in summer. This is a truly wild Atlantic dive requiring solid boat diving experience.

The SS Mohegan was a 3200-tonne Atlantic Transport Line steamer that struck the Manacles Reef in 1898, killing 106 passengers and crew. Her boilers and substantial sections of hull lie at 13–26 m and have become a living reef colonised by soft corals, anemones, and cuckoo wrasse. Grey seals frequent the site and are curious about divers, often swimming circles around them. The Mohegan is one of Cornwall's most atmospherically charged dives.

The Manacles is a treacherous reef system off the Lizard Peninsula that has claimed well over a hundred ships over the centuries, and today is a celebrated wreck and reef diving area teeming with life in Cornwall's clear waters. Conger eels, ballan wrasse, and spider crabs inhabit the broken Victorian-era wrecks, while porbeagle sharks patrol the outer reef in summer. Tidal timing is critical as strong currents make the site undiveable on the wrong state of tide.

Cornish Seal Dive Academy is a Falmouth-based BSAC and PADI school running drysuit and diver training programmes suited to the chilly, rewarding waters of the English Channel and Celtic Sea. Cornwall's tidal currents, kelp forests, and granite reef pinnacles host a surprisingly diverse marine community including playful Atlantic grey seals, cuckoo wrasse, spider crabs, and the occasional basking shark. Their specialist Cornish wrecks programme covers historical vessels stretching from Spanish Armada galleons to wartime convoy ships lying on sandy seabeds at 10–30 metres.

Penzance Ocean Divers runs boat charter dives and BSAC training from Penzance harbour, exploring the wrecks and reefs of Mounts Bay and the offshore Lizard Peninsula — home to some of the most spectacular underwater scenery in the British Isles. Visibility can vary with season and swell, but calm summer days reward divers with kelp cathedrals, jewel anemone-covered walls, and the bizarre alien architecture of sea fans growing in the warming Gulf Stream waters. The school runs dedicated shark and ray snorkel days throughout summer when blue sharks are reliably encountered off Land's End.