Lac Souterrain de Saint-Leonard

About

The Saint‑Léonard Underground Lake (Lac Souterrain de Saint‑Le ‑ Leonard) is a natural, navigable subterranean lake located in the Valais canton, just ten minutes from the town of Sion. Discovered in 1943 and opened to the public in 1949, the 300‑metre long pool is the largest underground lake in Europe. Visitors board small, compact boats that glide silently over 4 m of crystal‑clear water while a multilingual guide narrates the history and geology of the site. Each visit lasts about 30 minutes and is conducted in French, German, and English. Adults pay CHF 12 and children aged 5–15 pay CHF 7, while children under five enter free of charge. The lake is open daily from 10 am to 5 pm between 15 March and 1 November. Reservations are mandatory and strongly recommended, especially during peak tourist season; a booking can be made online or on the day of arrival, without the need to print a ticket. Beyond the underground lake, the venue also offers a new didactic space, a café, and acoustic concerts, making it a memorable destination for families, history enthusiasts, and curious travelers alike. The surrounding alpine scenery adds to the experience, with easy access from the nearby train station and nearby parking.

At a glance

• Typical visit: about 30 minutes

Tickets & pricing