Its highest point is 350 m (1,148 ft) asl and it lies about 2 km (1.2 mi) from the mainland in the entrance to Te Puaitaha / Breaksea Sound, north of the much larger Resolution Island.

It is covered in temperate rainforest and was the site of one of the first successful campaigns to eradicate rats from a sizeable island.

The pioneering eradication of brown rats, using brodifacoum in poison baits, was carried out by the New Zealand Department of Conservation (DOC) in May and June 1988 following the success of a pilot campaign on the adjacent, and much smaller (9 ha or 22 acres), Hāwea Island in 1986.

Since rat eradication various threatened species of New Zealand's native fauna have been introduced, or reintroduced, there.

These include the tieke (saddleback), mōhua (yellowhead), Fiordland skink and knobbled weevils.