Park at the Artigusse car park (1,600 m): subject to a charge during the summer season.
(S/E) Cross the footbridge over the Neste de Couplan and follow the path down to the track.
(1) Then climb up towards the Lac de l'Oule dam (1,820 m).
(2) At the fork, turn left towards the dam and continue to it.
(3) Continue along the path on the left, following the western shore of Lac de l'Oule to Cabane de la Lude (altitude 1818 m) and its beautiful summer pastures, which are ideal for picnics.
(4) Facing the hut and the dam, take the path on the left, which climbs up the eastern slope towards the Col de Portet and the Bastan Refuge: red and white GR®10 markings. Leave the Cabane de Bastan on your left and reach a fork (altitude 2120 m).
(5) Leave the GR®10 trail on your right and continue up the Bastan valley (GR®10 access). You will soon reach the Lac Inférieur de Bastan (altitude 2,141 m). Then walk along the small lakes before arriving at Lac du Milieu de Bastan (altitude 2215 m), where a short, easy slope takes you to the Refuge du Bastan (altitude 2250 m).
(6) Continue along the path to the Upper Bastan Lake before climbing, off the marked trail, a steep path on the right that leads to the Bastan Pass (altitude 2481 m).
(7) Continue to the right, heading south, along a cairned path along the ridge to reach the steep slope of Pic du Pichaley (2,626 m): enjoy the immense panorama.
(8) Descend the rest of the ridge to Col de Jétas, then climb back up towards Montarrouyet (2,473 metres).
(9) Stay on the ridge to reach Pic de Montarrouyes (2,462 metres).
(10) From there, follow the Soumaye ridge southwards, which descends in stages to the Col de Portet (2,214 metres), where you will find the GR®10.
(11) Turn right. Keep left at the two three-way junctions that appear in succession and continue between two chairlifts. You will reach a three-way junction.
(12) Continue on the left, following the track that passes between several chairlifts on the left and right. Continue for about 600 m after the last of these.
(13) Leave the track and take a path on the left to cut across a long bend, rejoin the track and continue downhill until you reach the edge of Lac de l'Oule. Continue to the left to reach the dam and the Refuge de l'Oule.
(14) Then continue on the right along the path that descends, passes at the foot of the dam and then turns sharply south. Return to the ascent route.
(2) Continue straight ahead, following the route in the opposite direction to the way you came, until you reach the car park (S/E).