Coastal fish are found in the waters above the continental shelves that extend from the continental shorelines, and around the coral reefs that surround volcanic islands. The total world shoreline extends for 356,000 km (221,000 mi)[3] and the continental shelves occupy a total area of 24.286 million km2 (9 376 million sq mi).[2] This is about 4.8% of the world's total area of 510.072 million km2.[3]