How to find it
Turn off the D290 at the turning marked La Combe and proceed to the electricity tower, where a track heads off to the right. Continue down this to reach a bridge over the river and follow the obvious track marked with red and white stripes steeply up the hill. Some distance further on, in the trees, a path also marked with red and white stripes leads off to the left, but one should continue ascending straight ahead. Continue up the track, still following the red and white stripes, until you reach a path going off perpendicular to the left, on a straight section of track, marked with a very faint blue circle on a rock standing vertically close to the ground, facing the direction you have just come from.
Following this leads to a limestone pavement where it appears that the track turns through an acute-angled turn to the right; at this point, one should continue straight on across the pavement to a cairn. Contour around the limestone, passing through some bushes on a small path, to reach a further area of limestone where the cave entrance is situated: an open slot under a very small rock bridge with fine views over the neighbouring hillside. From the CESAME hut this takes 30-40 minutes. Coordinates of cave entrance (WGS84 datum, UTM grid): 0612443 4916259.
Description
Entering the hole leads to two P-hangers for a Y-hang, providing a free-hang down the narrow first pitch. A P-hangered traverse then descends to the head of the first pitch, equipped with P-hangers for the Y-hang. Two deviations, firstly from a thread and secondly from a spit, lead down to a rebelay from two P-hangers followed by another spit rebelay (sling helpful, belayed from a spit) which provides a hang to the bottom of the pitch. 85m of rope should suffice to this point, together with 11 maillons, 3 hangers, 4 slings, 3 krabs (for a perfectionist rig).
At this point there is a level of large horizontal passages, with some good stalactites, as well as a prodigious amount of mud (a recurrent feature in this cave).
Standing facing the wall which you have descended against, about 5m to the left is a small slot at the base of the wall with a stal boss alongside. This can be descended leading to a crawl; turn right through a moderately tight window to reach a small chamber. A descending squeeze through a U-bend (best descended head first and facing the roof) leads to a widening where a P-hanger provides a backup for a further descending squeeze which opens onto a ledge at the top of the final pitch of 55m. This squeeze isn't too bad on the way down, but is difficult for anyone with a wide rib cage on the way up as there is pretty much nothing to push on with your feet and it is narrowest at the bottom, so you need to push yourself up with your arms and haul forward at the same time. Unfortunately it's too close to a pitch head to do without a harness. Paul got stuck and had to be hauled out by Haydon.
Alternatively, you can follow a sloping traverse above the slot to a passage in the wall, where a further traverse across a small hole (spits in place for a traverse line) leads to a descending tube emerging in the roof above the 55m pitch.
Both routes unite at a Y-hang rebelay off two P-hangers (all the anchor points are P-hangered from here down). A sloping descent leads to a rebelay just above a short vertical squeeze; the pitch opens out below this, where there is another rebelay (entirely free-hanging). Some distance below this is a large ledge with a distinctive conical stagmite, where one traverses to the right along a ledge to a new Y-hang for the final section of the pitch; the floor is reached after a final rebelay (where two P-hangers in a vertical line are provided, the purpose of which is obscure).
This leads to the lower horizontal level, which is spacious and very well decorated. The pitch lands part-way down a slope; up-slope (to the left) closes down quickly but has a fine crystal pool which is worth a look. Descending the slope leads to a substantial chamber, with several large passages branching off in various directions. In particular, continuing straight across leads via a short, sandy stooping-height passage to a chamber with striking mud formations.