Mount Gambier is located midway between Adelaide and Melbourne. The city is built on its slopes, in the center of the largest pine plantation in Australia. Caves and craters dominate the landscape of this extinct volcano which has been inactive for a few thousand years. Blue Lake, which changes from gray to an intense turquoise blue in November, and back to gray at the end of summer, is one of four crater lakes in the area. Piccaninnie Ponds which is 75 meters deep is a world famous for cave divers.