Col de Bas (1537 m) walks

Since the fire in July 2026, the terrain has been very unstable (frequent rockfalls) on the GR®10 towards the Ayes Lake, and this section of the path is therefore closed. Consequently, the ONF recommends an alternative route, the details of which are given below, between the Maison du Valier and the Col de la Core. The start and finish points of this stage are accessible by car.

First day of this trip to the Refuge d’Eylie. A day not to be underestimated.Set off from Sentein along an old track, then take the small road up to Bencarrech, joining the GRP® Tour du Biros. The GRP® in the Isard Valley crosses to the other bank via the Illa Maria footbridge. It then passes the Passerelle du Pichès on the right and begins a steep climb. From there, a PR® trail leads to the Col des Cos (mountain hut, fountain). This is followed by a tricky descent due to fallen trees blocking the path (PR®). After at least 6 hours’ walking, including breaks, with 1,200 m of ascent and 900 m of descent, the Eylie restaurant and bar is a welcome sight.

First stage of the Petit Tour du Biros.From the Anglade car park, a steady climb along theGRP®® Tour du Biros to the Passerelle des Pichès, then a detour via the Chapel and the Cabane Forestière de l'Isard.Then, after returning to theGRP®®, you arrive at the Cabane d'Illau.This is followed by a steep climb up to just below the Étang d’Araing dam and finally the arrival at the Refuge Jacques Husson de l’Étang d’Araing.This stage is only feasible when there is no snow, from late May until the huts close or the first snowfall begins.

Second day of this trip to the Refuge d’Eylie. A day not to be underestimated.Classified as difficult due to an average gradient (slope) of 24% from (1) to (3). Afterwards, the GR®10 access trail – GRP® Tour du Biros – is very narrow, poorly maintained and at times dangerous due to low-lying, slippery rhododendrons: it is a north-facing slope. There are moments of respite in the woods, where the path is fairly wide and very well signposted. From the Col des Cassaings onwards, conditions improve. The highlights of this balcony trail are the numerous viewpoints from (3) to (4) and from (4) to (6).After at least 6 hours’ walking, including breaks, with 900 m ascent and 1,150 m descent, the arrival at the Ostal du Biros in Bonac is a welcome relief. From there, it’s a 25-minute drive along a very quiet road back to Sentein (E).

Third and final stage of the short Tour du Biros.The return route follows a very interesting and well-marked path, passing through Col des Cos.A lovely hut with a new roof, open to the public, is available at this pass as a new hut has been refurbished for the shepherd(s). There is also a water source at this spot.A very beautiful descent until you reach the GRP® Tour du Biros.Pass by the lovely Passerelle des Pichès footbridge.You pass through the hamlets of La Peyre and Frechendech before arriving at the car park.This stage is only possible when there is no snow, from late May until the mountain huts close or the first snowfall begins.

Second day of the Petit Tour de Biros.From the refuge, head due east along theGR®®10to the junction at the foot of the dam (passed the previous day).Continue uphill along theGR®®10. Reach a fork at the Col de la Serre d’Araing.Head left for a round trip to the Pic de l'Har. A stunning 360° view.Then descend via theGR®®10to the Mines de Bentaillou.Head north and follow theGRP®® to the Col de la Catauère (Plateau de Rouge).Then head down theGR®®10to Eylie.This stage is only feasible when there is no snow, from late May until the mountain huts close or the first snowfall begins.