On leaving the Vielha Tunnel in the direction of Lleida, after 900 m, you'll see a parking area on your left. Turn right onto an access road which allows you to cross the N-230 in complete safety.
From the large truck parking area, take a small road where vehicles over 3.5 t are not allowed, and park a little further on in an area on the edge of the forest.
(S/E) Continue southwards, crossing the Ribagorzana and arriving after a few metres at a crossroads. On the left, the road continues towards the Refuge Forestal de Conangles (where you can get something to eat on the way back). Turn right onto the Besiberri track for about 700 m, until you come to a footpath on the left.
(1) Follow this path to cut all the twists and turns of the uphill track and stay as close as possible to the torrent coming from Besiberri Lake.
It climbs steeply through the forest, after 100 m, cross the track for the first time, continue straight ahead, cross the track a second time at a hairpin bend and continue straight ahead on the path. Pass a waterfall, cross the track a third time at a hairpin bend and continue straight on.
Rejoin the trail at its terminus on the edge of the torrent, at a flat spot where you can refuel the fire-fighting trucks.
(2) Continue on the only path up to the lake and the Besiberri Refugi. It climbs steeply, first on the right bank, then over a footbridge to the left bank of the torrent and on to the lake spillway.
(3) At the Besiberri Lake, enjoy a magnificent view of the Cirque des Besiberri. The path remains on the left bank of the lake and continues through a rocky chaos to an idyllic flat grassy spot for a rest.
(4) For the return journey, retrace your steps back to the track.
(2) Follow it downhill to the parking area (S/E).