The Big Green Island, part of the Big Green Group within the Furneaux Group, is a 122-hectare (300-acre) granite island with limestone and dolerite outcrops, located in Bass Strait west of Flinders Island, in Tasmania, in south-eastern Australia. The island is partly contained within a nature reserve with the rest being used for farming; and is part of the Chalky, Big Green and Badger Island Groups Important Bird Area.