Itinerary: Rioseco-Castañero del Castrín-El Castañeru Montes-Rioseco.
Distance: 6 Km. 500 m.
Duration: 2 h. 15 min.
The route starts in the town of Rioseco, capital of Sobrescobio situated over a fertile meadow over the waters of the Nalón River. In the early sixties, the dams Rioseco and Tanes were built, in the neighbouring Caso, with the double purpose of providing drinking water and electricity. From the reservoir of Rioseco, once purified, the waters are taken to central Asturias.
The itinerary starts in Rioseco on the road leading to Soto de Agues, but just after crossing the reservoir, take the left turn towards El Llosu, where there is another turning. Take the track to the right that gently climbs between chestnut trees to reach the fields of La Trepe. From here the route continue its ascent on a cart path, passing the fountain of El Focarón. You will soon reach the fields of La Cruz or El Gayeteru, closed with the wooden gates that are so characteristic of the Alto Nalón. A bit further up, you will find the fields of Cueria, where you will find several huts and stables, where you can take a short break to enjoy the beautiful view of the town of Rioseco and the reservoir of the same name.
The path continues climbing; entering again a chestnut tree forest, after crossing the gate, with should be kept closed. Following the main path, leave the Roces grazing area behind, where there are three huts, and to the right, several fields, to reach an open plane. On the left hand side there is a stone wall. In front of this plane you will see two stables- go around them on the left to reach a crossing of three paths. Here, take the path to the right leading to the chestnut forest of El Castrín. It is worth while at this point, to take a break and enjoy the beautiful view of the Agues valley, with the Foces Llaímo in the background, and the peak Cuyargayos in the horizon.
Finally descend down the track which crosses the chestnut forest El Castrín to enter the Castañeru Montes, and taking all the paths to the left, return to the start of the route.