How to find it
From Vallon, head for Roums and then drive north along the D104 to Aubenas. Follow the signs through the town heading for Privas (D304; the same direction as Montelimar until a large roundabout where you need to turn left). The road heads through a tunnel and then, after a right turn at a roundabout, continues to St Privat. Just after the town, take a right turn onto the D259 to Lussas. When you reach the village, turn left towards Darbres (D224) at a crossroads in the middle of the town. Follow the road until a turning to St Laurent sous Coiron is seen on the left; turn off here and follow the road until a junction is reached, marked St Laurent to the right and Privas to the left. Turn to the left (the village to the right and the view is well worth seeing though) and follow the road for about a mile and a half. On the left, a fairly well-worn (gravelly/stony) track descends to the left. There is a cattle grid almost immediately down the track which is visible from the road. Continue down the track, passing over another cattle grid, until you reach an old stone building with newish rectangular-section chimney pots and old farmyard machinery outside. Park here and walk to the corner of the field closest to the building. Cross the field diagonally down and to the left to reach the opposite corner where a good path starts. Follow this until an obvious junction is reached (large somewhat knarled tree on the corner) with the track continuing ahead and another track going back and down to the right. Take the track heading down until you see a small cairn on the left. Turn left at the cairn onto a path which skirts the hill and then descends to a rock outcrop with an old stone camp fireplace overlooking a gorge. The cave is found just down and to the right in the outcrop, a small entrance marked "SCA 96" in red paint. Total 560m from the parking spot and 240m from the junction at the knarled tree; at least a good hour's drive from Vallon.
See Speleo Sportive en Ardèche.