It is the largest of the Gambier Islands, covers an area of about 10 square kilometres (3.9 sq mi) and is partly privately owned.

It was originally settled in the mid-19th century as a farm for breeding horses for the British Indian Army, with various agricultural activities such sheep and cattle grazing and wheat cropping continuing for the next 130 years.

Maud Baillie (born Golley in 1884) was raised on the island and was noted as a skilful furniture maker and wood carver.

[3] During World War II, Wedge Island was used as a radar station by the Royal Australian Air Force (RAAF).

[4] An account of the wildlife on Wedge Island from 1928 reads: "The penguins were busy with their half-grown youngsters, and after dark the night echoed to their weird and ghostlike cries.

Quail were plentiful among the grass paddocks and flew up almost from beneath our feet, while high above our heads a pair of wedge-tailed eagles wheeled and circled then planed slowly down to alight upon a lone pinnacle of the rocky western coast.

[11] A 1928 account of the Haycocks (off Wedge Island) describes a party from the Avocet filming the "large number" of seals there.

[14] Southern hairy-nosed Wombats were introduced in 1971 to boost tourism appeal and there are now about 300 living on the island.