St-Léonard underground lake

In the heart of the majestic Valais Alps, nestled between Sion and Sierre in Switzerland, lies the captivating and mysterious Lac Souterrain de St-Léonard. Imagine exploring this hidden gem, diving into its crystal-clear waters and discovering the enchanting secrets of a fascinating underground world. An unforgettable adventure awaits you in this place of mystery and breathtaking natural beauty.

A privileged witness to the formation of the Alps, this navigable underground lake nestles in the hillside between 30 and 70 metres below the vineyards. At 300 metres long, it is the largest natural navigable underground lake in Europe. As the cave is completely submerged, all visits are made aboard rowing boats that can accommodate up to 40 people. In complete silence, multilingual guides will take you on a tour of this fascinating world. During a 30-minute guided tour, you'll glide over the clear waters of the lake and learn to decipher its mysteries.