Parc naturel régional Gruyère Pays-d'Enhaut - At Chaudanne Spring, water seems to emerge from the depths of the Earth. Water seeps into the ground on the east slope of the Vanils Range and joins an interminable underground network of subterranean galleries, only to reach the surface after travelling several kilometers underground. Located several meters below the main road (Bulle – Château-d’Œx), the spring is circular in form with a diameter of about 2 meters. It spills into a flooded funnel, which marks the entrance to a subterranean water network.
The Chaudanne is a vauclusienne spring, which means that its water climbs vertically through pressurized subterranean channels before reaching the surface. Rising from a depth of several hundred meters, this site constitutes one of the deepest submerged galleries in the Prealps. The site is made even more special by the fact that it has been explored by speleologist-scuba divers. In 1988, scuba diver Cyrille Brandt reached the depth of -143 m, which was the deepest speleological
dive in Switzerland at that time. In 2009, a new record was set with a depth of -175 m at Chaudanne Spring. The dive lasted more than 9 hours.
The water temperature is stable at around 8°C, which is cold for divers, but relatively warm when considering the altitude of the catchment basin (880 m to 2389 m). The stability of the temperature is further evidence that the water spends quite a bit of time in subterranean networks between seepage and emergence at Chaudanne
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