The Pacific has a record of 25,000 islands. The islands which lie entirely within the ocean are grouped as either belonging to Polynesia, Melanesia, and Micronesia. Melanesia has the largest of the islands of the Pacific, named New Guinea, as well as groups of islands such as New Caledonia, the Bismark Archipelago, Fiji, the Solomon Islands, Vanuatu, and Sana Cruz. Micronesia is situated north of the equator and includes the islands of Kiribati, Mariana Island, the Marshall Islands, and the Caroline Islands. Polynesia ranks as the largest, with such regions as Eastern Island, Tuvalu, Austral Islands, Tokelau, Tuamotu, Samoa, and the Cook Islands. The Pacific islands are classified into four primary types, and they include the uplifted coral platforms, continental islands, coral reefs, and high islands. here