Natural cavern of 33 metres in diameter and 75 metres deep, the Padirac chasm located on the Gramat Limestone plateau, formed when the roof collapsed. In the heart of this cavity, 103 metres below ground to be precise, flows a underground river. Visitors descend 75 metres via a lift or staircase and go to the end of a gallery where they board boats for the first leg of the guided tour by river. 500 metres further, the visitors continue the circuit on foot through a series of beautiful rooms: the Salle du Lac de la Pluie (Rain Lake) and the pendant-like Pendeloque (giant stalactite), the Salle des Grands Gours with a lake, and then the Salle du Grand Dôme with its impressive 94-metre-high ceiling. All these natural formations are awe-inspiring.