Reservoir of Tanes Nature · Sobrescobio, Nalón, Asturias A sheet of water hemmed in between limestone walls in the middle of the Redes biosphere reserve, making use of one of the narrows of the Nalón. It is of considerable ornithological interest and acts as the upper reservoir of a pumped-storage power station buried inside the mountain. Photo: ALusitana (CC BY-SA 3.0 es) What to see and do in Sobrescobio