during the summer to around , causing calcium carbonate to precipitate out of the solution and enabling microcrystallites of calcium carbonate to form. This results in scatter of the blue wavelengths of sunlight. During winter, the lake becomes well mixed, and recent research indicates that during this phase of the colour cycle, the lake is somewhat murkier due to the redistribution of tannins and calcium carbonate particles throughout the lake. Solar elevation has also been found to influence the perceived colour of the lake. The movement of planktonic life forms within the lake during the seasons and during the day may additionally play a part in the colour change. Studies Bathymetric surveys located the deepest point in the lake at in 1967. Major diving exploration of the lake first occurred in 1985. Cave diver Peter Horne conducted temperature and visibility studies and made discoveries of a freshwater sponge species and other invertebrates. This exploration also discovered the Stromatolite Field, a collection of hollow rock formations that are found along the north-eastern perimeter down to a depth of . In 2008, permission was granted by SA Water for another diving exploration of the central and deepest parts of the lake. On this dive, core samples from the calcite-silt covered lake bed were collected where water temperature drops to . Gordon's leap In July 1865, Adam Lindsay Gordon performed the daring riding feat known as Gordon's Leap on the edge of the Blue Lake. A commemorative obelisk erected there has an inscription which reads: This obelisk was erected as a memorial to the famous Australian poet. From near this spot in July, 1865, Gordon made his famed leap on horseback over an old post and rail guard fence onto a narrow ledge overlooking the Blue Lake and jumped back again onto the roadway. The foundation stone of the Gordon Memorial Obelisk was laid on 8th July 1887 Gallery See also List of lakes of South Australia References Further reading Emeny, J., Turner, G., Turoczy, N.J. and Stagnitti, F. (2006) The influence of weather and solar elevation on perceived colour of Blue Lake, Mount Gambier, South Australia. Transactions of the Royal Society of South Australia. 130(1) 101–108. Horne, P. (1985) Report on an exploratory study of the underwater environment and biology of the Blue Lake, Mount Gambier, South Australia 21–25 January 1985 () and subsequent study reports July 1985, 1987, 1989, 1991 and