Carnac Island is a 19-hectare, A Class, island nature reserve about 10 km south-west of Fremantle in Western Australia .home to Australian sea lions, bottlenose dolphins and a large range of marine bird life. It is particularly noted for the abundance of snakes, particularly tiger snakes, which live there. For this reason, very few people venture there. There is no permanent fresh water, providing a challenge for the animals that live there. The origins of the tiger snake colony has attracted significant debate and research into how that species has adapted to a harsh island habitat.
Carnac is supports a large colony of the vulnerable fairy tern, as well as small numbers of other nesting seabirds.