Fosse Dionne (Tonnerre), source du basilic

Tonnerre

At the foot of the old town of Tonnerre, water rises from a round stone-edged basin: the Fosse Dionne. It is a so-called Vauclusian spring, fed by an underground network of the limestone plateaux. Its name would come from ‘fosse’ and Divona, an ancient goddess of the waters. According to tradition, a basilisk, a serpent whose gaze kills, lived here. Saint John, abbot of Réome, is said to have dug out its lair; the water flooded the cavity and drowned the beast. This tale appears in Pierre Petitjehan's description of Tonnerre, in 1592, but an account in the life of the saint, written in 659, already mentions the place. Another legend makes the Devil a horseman who escapes through the bottom of the abyss. According to Tonnerre-patrimoine, these stories reflect fear of the fevers of the neighbouring marshes, the basilisk representing the disease. In 1758 the father of the chevalier d'Éon had a wash-house with a circular basin built around the spring, with a covered lean-to for the washerwomen. The wash-house has been listed as a historic monument since 1920. Divers have explored the flooded passage since 1955; after fatal accidents, the town banned all diving in 1996.

Getting there: In the town, rue de la Fosse-Dionne, in Tonnerre. The wash-house and its basin can be viewed from the street; any opening hours and whether it is free have not been verified. Diving has been forbidden there since 1996 (two divers died in 1963, another fatal accident preceded the order): never bathe there. Coordinates taken from OpenStreetMap (‘Fosse-Dionne’), which agree with Wikipedia EN.

Opening times and access details are given as a guide only: check before you set out.

Ambient sound