Tourism is the largest economic industry in the Maldives. A tourist resort in the Maldives consists of an exclusive hotel on its own island, with its population entirely based on tourists and work force, with no local people or houses. These islands developed for tourism are approximately 800 by 200 metres in size and are composed of sand and coral to a maximum height of about 2 metres above the sea. In addition to its beach encircling the island, each island has its own "house reef" which serves as a coral garden and natural aquarium for scuba divers and snorkelers. The shallow water enclosed by the house reef also serves as a large natural swimming pool and protects swimmers from the ocean waves and strong tidal currents outside the house reef.