Lac Souterrain de St-Léonard

The St-Léonard Underground Lake is situated between Sion and Sierre in the heart of the Valaisan Alps. A privileged indicator of the formation of the Alps, this navigable underground lake nestles in the hillside at a depth of between 30 and 70 metres.

With a length of 300 metres, it is the largest natural, navigable underground lake in Europe.

During a 30-minute commentated visit, you can let yourself glide on the crystal clear waters of the lake and learn how to decipher its mysteries.