On the D901 towards Castanet, park in the car park near the road bridge over the lake.
(S) From the car park, cross the road and take the small path towards Gratassac. The steep path climbs to the summit where the cross stands. Enjoy the 360° view from here.
(1) Continue along the route, which can be difficult at times as it is not regularly marked. However, look out for the yellow markings or cairns that mark this path. Follow an almost horizontal traverse to reach the start of the descent.
(2) Turn right and begin the descent, passing close to the Via Ferrata. Cross two small streams, the Ravin du Combre and then the Ravin de Charebouisson, before reaching a tarmac road at a hairpin bend.
(3) Turn left until you reach another tarmac road.
(4) At the junction, turn right and cross a narrow bridge over the Altier at the far end of the lake to reach the Castanet car park.
(5) Follow the same route back to the car park at (S/E)