Approach to Nocito: from Huesca take north direction to Sabiñanigo. After the Puerto de Monrepós and before Sabiñanigo take a bad road to Ordoves and valley of Serrablo. After 9 km follow to the right for the track without asfalt for 10 km to Nocito.
Time to summit: 4h 30 min.
From Nocito (910m) take the track near the river Bail. After a old mesón we enters in the Natural Park (signal, 30 min).
We will pass the first one of the fords of river without problems. In whole the route supposes approximately 6 or 8 fords that in epochs of major wealth they can force to take off the boots.
We are in the ravine of the Pillera penetrating in the narrow canyon between puddles of water and curious calcareous formations originated by the action of the water for centuries.
After approximately 1 hour we come to a detour indicated with a great cairn. We continue to the left side penetrating in a nice forest. It is necessary to be attentive to the cairns for follow up and not to descend. After a small rocky step we will come to a new path that ascends little by little. After a sudden draft to the right we will come to the Col of Chemelosas at 1386 meters (2h).
To flank the ravine we will meet obliged to lose something of height. On having returned to up we reach with facility the Col of Petreñales (1558m, 2h 30min).
From here is exactly the same route of south to the summit (see South route).
Walking poles, water.
In winter: crampons and ice-axe.