Rubacao and Aguasal are the two rivers draining the mass of Valnera and feeding the river of Pandillo.

The path between both rivers allows us to recognise essential values of the Pas world in one of the most emblematic landscapes of the eastern mountains of Cantabria: the east wall of Valnera.

Pas river offers different landscapes in the different seasons of the year, always linked to mans presence in these mountains.

The route starts in the neighbourhood of Portilla, a group of cottage without a square or any other usual village services. We ascend to Canal de Selpedrizo, taking the  different pathways that are available, towards that north there is a beech forest.

We leave behind the cottage neighbourhoods of Portilla, La Brinía, El Sillar or La Cotera, before reaching those of Orra and Hormías, to then descend through the clear pathway that takes us to El Siar.

On the last stage of this route, towards Aguasal, we cross the forest next to Siar. Before ascending to La Estribera, we recommend ascending to the pasture of Aguasal and seeing the dejection cone formed by Sel de La Garma when joining the main river. Once here, we only can descend to La Estribera by following Aguasal river. To finish the circuit, we need to descend to the starting point in Portilla, following the road coming from Vega de Pas.