Approximately 15 kilometres south of Mount Gambier lies what seems to be a deep lagoon in the middle of nowhere. The 40-metre or so circular pool is surrounded by cliffs that rise about 8 metres above water. I wouldn't blame you if your first instinct was to step back as you look over its edge.
This body of water is known as Little Blue Lake. It is a water-filled sinkhole with a depth of 47 metres formed by the collapse of its surface layer causing a hole in the ground. An artificial cutting has been made to install stairs and a floating pontoon for safer access. Visitors are prohibited from jumping off the cliffs.
The lake's naturally cool waters (a constant 12 degrees) is popular with experienced swimmers and authorised divers. The emphasis here is "experienced" and "authorised" as there are no patrols around the area. Little Blue Lake is remotely located on Mount Salt Road off the Riddoch Highway between Mount Gambier and Port Macdonnell.