The Blue Lake is one of only four cirquelakes found in mainland Australia, the other three, Cootapatamba, Albina, and Club are shallower than BL and are held entirely by terminal moraines. Its valley contains the best-developed glacial features in the Kosciuszko National Parkalpine area of New South Wales. It was recognised as a wetland of international importance on 17 March 1996 when a 320-hectare (790-acre) area, comprising the lake and its surrounds, including nearby Hedley Tarn, was designated Ramsar Site 800 under the Ramsar Convention on wetlands.
Blue Lake is 16 hectares (40 acres) in area and 28 metres (92 ft) deep. Its surface is entirely open water, with boulders reaching the shore in the east and north east, and the other shores being pebbly. It lies about 28 kilometres (17 mi) west of Jindabyne and 3.5 kilometres (2.2 mi) north of Charlotte Pass at an altitude of 1,890 metres (6,200 ft) above mean sea level, in a glacial landscape.
The lake was formed when glaciers flowing from the Great Dividing Range converged and carved out a basin in the granitebedrock. It receives water from Blue Lake Creek, originating from Mount Twynam and from snowmelt. The surface of the lake is frozen for about four months of the year; it overflows in spring with the melting of the snow while, during the rest of the year, the water level remains stable.
Peter Morris and John Eisman climb Mindbender at Blue Lake in the Snowy Mountains, Australia, 1976
Blue Lake may be reached by a 2-hour walk from Charlotte Pass. Human activities in the area include environmental education, bushwalking, skiing, and ice climbing. Since all five glacial lakes in the Kosciuszko alpine area are naturally low in nutrients, in order to maintain nutrient balance and prevent contamination, camping is not permitted in the catchments of the glacial lakes.