Under this layer of ice and snow, it is difficult to recognise Lake Pavin, the youngest crater lake in mainland France and the emblematic representative of the territory's most recent volcanic system. Bordered by ancient forests (beech or fir forests), it forms an almost perfect circle of 2,624 feet (800 metres) in diameter at an altitude of 3,927 feet (1,197 metres) in the Sancy massif, in the municipality of Besse-et-Saint-Anastaise.