Island
An island or isle is any piece of sub-continental land that is surrounded by water. Very small islands such as emergent land features on atolls can be called islets, skerries, cays or keys. An island in a river or a lake island may be called an eyot or ait, and a small island off the coast may be called a holm. A grouping of geographically or geologically related islands is called an archipelago, such as the Philippines.
Sand island
A sand island is an island that is largely or completely made of sand. The largest sand island in the world is Fraser Island. Other examples of large sand islands are Moreton, North Stradbroke and Bribie, Islands which lie south of Fraser Island off the east coast of Australia.