Grotte des Planches
This cavern lies deep in the Reculée des Planches, a box canyon - the highest of its kind in the Jura. Inside, the galleries illustrate how the waterways flow and continue to burrow down into the ground. The lower gallery becomes a conduit for the Cuisance when water levels swell, and is occupied by a string of lakes with transparent bluish waters - over a distance of 800m - during the dry period. Erosion has created long galleries, chimneys, gour pools and an exceptional series of potholes.