An island or isle is a piece of subcontinental land completely 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. Sedimentary islands in the Ganges Delta are called chars. A grouping of geographically or geologically related islands, such as the Philippines, is referred to as an archipelago.

Kangaroo Island, also known as Karta Pintingga, is Australia's third-largest island, after Tasmania and Melville Island. It lies in the state of South Australia, 112 km (70 mi) southwest of Adelaide. Its closest point to the mainland is Snapper Point in Backstairs Passage, which is 13.5 km (8.4 mi) from the Fleurieu Peninsula.