The Fosse Dionne, a treasure just a stone's throw from the campsite 💧

In Tonnerre, the Fosse Dionne has fascinated people for centuries. This natural spring, with its crystal-clear, deep blue waters, gushes forth in the heart of a circular basin surrounded by an old 18th-century wash house. Its flow is impressive… and its mystery remains, since the underground network is still only partially explored.

Today, this iconic site in Burgundy-Franche-Comté is at the heart of a restoration and enhancement project. Roofs, masonry, the basin… a whole range of work is underway to preserve this exceptional heritage and improve the visitor experience.

Selected for the 2026 Heritage Lottery , the Fosse Dionne confirms its central role in Tonnerre's appeal. Its surroundings will be progressively redeveloped to offer new viewpoints and an enhanced visitor experience.

From Camping La Cascade, it only takes a few minutes to get there and discover this unique place, between nature, history and mystery.