Park in the Col du Fût d'Avenas car park.
(S/E) Cross the D136 road with caution and take the small road opposite the car park exit. Then turn off to follow this small road on your left. Ignore the first path on the left.
(1) Take the next one to begin the climb. When you reach a flat section, turn left at the intersection and follow the path to rejoin the road. Continue to the right.
(2) Take the path on the left just before the water tower and continue on this same path to Croix Callet. At this intersection, take the path that enters the woods slightly to the right: do not follow the one directly to the right.
Follow this path through the woods. When you reach a fork, turn left onto the left-hand path and continue along this main path. After two steep climbs, you will reach Croix de Rochefort.
(3) After the cross, begin the descent on the small path opposite the path you arrived on. Continue downhill until the path widens, then go straight ahead, leaving a path on your left. Continue until you reach a small road.
(4) Turn left. Follow the road to the Croix du Py.
(5) At this intersection, continue on the path opposite. After a few dozen metres, turn left and continue climbing on this wide forest path. At the top, follow the path that bends to the right and descend until you reach the road near a picnic area.
(6) Turn left, then quickly take a path on the right, leaving the small road on the right that starts at the same level. Follow this path along the meadows on your right, ignoring another path that branches off to the left.
(7) When you reach the woods, turn right at the intersection. Continue downhill towards the south-east and turn left when you reach theGR® 76. Continue downhill, following theGR®, which turns sharply to the right and crosses a stream (Grosne Orientale) before coming to a crossroads just after.
(8) Take the second path on your right and begin the climb towards the village of Avenas. Continue climbing, leaving the access road to the hamlet of Les Prés on your left, to arrive at a small road in the village a few metres from the D18E.
(9) Follow the road to the left to cross the village and, at the exit, keep left. Go down this road, then turn right at the bend to pass between the buildings of the Aubépin farm.
(10) Continue along the path on the left, which passes behind the houses. At the top, turn right and continue along this path, which turns into a road a little further on. Continue straight ahead to reach the Col du Fût d'Karstic Cave and your starting point (S/E).
. Be careful between markers 7 and 8: it is better to follow the GPS route rather than the "GR" marked on the trees. The route took 3½ hours.