Lake St Clair is a lake in the Central Highlands area of Tasmania, Australia. It forms part of the Cradle Mountain-Lake St Clair National Park. It has a maximum depth of 200 m, making it Australia's deepest lake. The Tasmanian Government has moved to allow development in national parks and conservations areas. An 'In principle' permit has been granted for the establishment of an 'eco-friendly' resort at Pumphouse Point at Lake St Clair.