The marine life of Sark, like that of the other Channel Islands, is a fascinating mixture of species from the north and those from much further south. The level of biodiversity is high and some of the sea creatures which live here, such as the Anemone Prawn and Black-face Blenny, are rarely seen around the coast of the British mainland. The Ormer, a large mollusc similar to an Abalone, is found only around the Channel Islands and the adjacent coast of France. The huge tidal range here, up to ten metres, means that the waters around Sark are constantly in motion with currents up to ten knots. Add to this the countless half submerged rocks and numerous rocky reefs and islets and it's easy to see why visiting yachtsmen find Sark's waters so challenging. The great tidal range also means that at low water a rock pool explorers paradise is revealed while the island's clear waters are perfect for scuba diving. The rocky reefs are home to several species of cold water coral including the Pink Sea Fan and Sunset Cup Coral, both listed in the UK Biodiversity Action Plan for their rarity.
The jewel in the crown of Sark's marine habitats is the Gouliot Cave system, a network of sea caves in the Gouliot Headland. The caves are open to the sea from both sides of the headland and at high tide are submerged by the strongly surging water. At half tide down the current slackens for a few minutes allowing scuba divers to explore the wealth of marine life growing on the walls and during extreme low spring tides the caves are accessible on foot. The Gouliot Headland and Caves were designated as Wetlands of International Importance under the Ramsar Convention in 2007 and are the only sea caves in the British Isles to receive such recognition.