Trailhead: from village of Benasque take the road to Hospital de Benasque. After the signal of Vallibierna and Baños de Benasque and before the Hospital we cross the Puente de Literola (signal) and we leave the car in the little parking. If you want near this road is possible to sleep in many campings the previous day. In summer take the bus in Benasque to Llanos of Hospital (every 30 minutes).
The path begin in the left side of the road near the little river across the forest. After the forest we will appear in a plain always to the right of the river. We will happen near the hut of Forcallo but we continue towards the right gaining height for the hillside. It is necessary to give many attention to the cairns that indicate the way to us up to coming to a zone rightly on the small lake of Literola. From this point there are two options:
-More direct, that it is necessary to avoid if there is snow for the great inclination that has, is to descend to the small lake and to continue for the channel that we have rightly face up to a hill near the top lake. Important: this way is complicated and even dangerous with snow (at the end of spring is posible the presence of holes and breaks under the snow).
-Another option is to follow for the right the marks to gain height for the path between the rocks up to a point in which we will descend a little bit to the same point over the channel of small lake. It is not necessary to come to the top lake that stays to the right since we will go to the left side changing totally direction in search of Ubago's col (2710m, 3 h). Here we join the route that comes from Estós. Now we are on the loin typical of the shoulder of the Perdiguero with his big and problematic stones about which there speak all the persons who climb to this mountain. It is an easy but heavy area and something long to reach first the Hito Este (East Milestone, 3170m) and finally the principal summit of this great mountain (3222m, 5 hours).
It is advisable the approach to the Hito Oeste (West Milestone, 3176m) in 15-20 minutes from the top with a magnific view of Portillon de Oô and the principal summit of Perdiguero.
The normal descent is for the same route. If you want it, it's possible to take the ridge of Literola from the principal summit and we climb 4 peaks of 3000 meters (Tuca de Literola, Pico Royo, Punta de Literola and Aguja de Literola), but the hike is long (11-12 hours, including the descent). After the ridge we arrive to Col of Literola and from here take to the left to the top lake of Literola and back to the normal route to small lake (or upper way if remain the snow in the channels over the small lake).
In winter crampons, ice-axe.