Sugarmouse Island is an unpopulated islet located close to the south-western coast of Tasmania, Australia. Situated some 2 kilometres (1.2 mi) south of where the mouth of Port Davey meets the Southern Ocean, the 0.54-hectare (1.3-acre) islet is one of the eight islands that comprise the Mutton Bird Islands Group. Sugarmouse Island is part of the Southwest National Park and the Tasmanian Wilderness World Heritage Site.