Underground lake of St. Léonard.

The offer is available in the following categories

  • The largest underground lake in Europe.
  • Guided tour by boat.
  • 10% discount on admission.


The underground lake of St. Léonard is located between Sion and Sierre in the heart of the Valais Alps. 

More than 300 metres long, it is the largest natural and navigable underground lake in Europe. On a trip of around 30 minutes, multilingual guides take you on a tour of discovery of this fascinating environment. At the entrance to the site, visitors can enjoy an attractive terrace, a gift shop and an educational area.