(0h0min; 0 kms) Sallent de Gallego (1,288m) Leave the village behind via a track that initially runs parallel to the river. After a few minutes you turn left at the crossing, where the track turns into a path and joins the road rising up to la Sarra reservoir. Follow it to the reservoir. Just before that, a narrow path emerges on the left, soon becoming a wider path, that leads you round the reservoir in about 15 minutes.

(0h55min; 3.6 kms) Tail end of la Sarra reservoir (1,420m). Entrance to the Ordesa-Viñamala biosphere reserve. On the other side there is a small car park and a bar-restaurant. You leave las Faxas bridge behind, without crossing it, and soon afterwards a leisure park (Plana Tornadizas). The path heads into the woods and rises up through Aguas Limpias valley along the right-hand bank. You cross a number of ravines; Bozitero, el Ministirio, Balsaroleta and el Garmo Negro before reaching el Paso del Onso, a narrow point with great rocky outcrops. You then pass Llano Cheto where the waters merge with those coming from Arriel ravine.

(2h00min; 7.6 kms) Crossing to the Arriel lakes (1,735m). You continue to head up the valley along the river banks, the path gets tougher, the valley opens up and you can finally make out the dam wall at Respomuso. The path passes by the Virgen de las Nievas chapel (next to the dam) and continues around the reservoir along the right-hand side.

(3h15min; 11.2 kms) Respomuso Auberge (2,200m).