Coral reef to form fringing reefs, and can eventually grow become a barrier reef. Where the bottom is rising, fringing reefs can grow around the coast, but coral raised above sea level dies. If the land subsides slowly, the fringing reefs keep pace by growing upwards on a base of older, dead coral, forming a barrier reef enclosing a lagoon between the reef and the land. A barrier reef can encircle an island, and once the island sinks below sea level a roughly circular atoll of growing coral continues to keep up with the sea level, forming a central lagoon. Barrier reefs
Deep-water coral off Africa’s west coast. In addition to ocean bottoms, scientists find "Lophelia" colonies on North Sea oil installations, although oil and gas production may introduce noxious substances into the local environment. The world's largest known deep-water "Lophelia" coral complex is the Røst Reef. It lies between deep, west of Røst island in the Lofoten archipelago, in Norway, inside the Arctic Circle. Discovered during a routine survey in May 2002, the reef is still largely intact. It is approximately long by wide. Some further south is the Sula Reef, located on the Sula Ridge, west of Trondheim on the mid-Norwegian Shelf,