This lake owes its existence to the Volcan du Tartaret, one of Auvergne's youngest, which stopped the flow of the Couze River when it erupted. This vast (60ha) but shallow (4-6m) natural reservoir boasts a lovely setting dotted with islets. It has jagged shores, except to the north, where the D 996 skirts along it, and to the southeast, where a large beach has been created. The rocky needle rising to the north of the lake is the waterfall, Saut de la Pucelle (100m).