Louisa Island is an island with a short sandy tombolo, located adjacent to the south-western coast of Tasmania, Australia. The irregularly shaped 23-hectare (0.089 sq mi) island is part of the Maatsuyker Islands Group, and comprises part of the Southwest National Park and the Tasmanian Wilderness World Heritage Site. The island's highest point is 80 metres (260 ft) above sea level and, at low tide, the island is joined to the mainland by a 250 metres (820 ft) sand spit.