Los Valles del Oso

Los Valles del Oso

Los Valles del Oso, incorporating Proaza, Quirós, Santo Adriano, and Teverga, are defined by dramatic limestone mountains, deep river-carved ravines, and dense Atlantic forests in central Asturias. Formed within the rugged Cantabrian Mountains, the region’s geography transitions from vertical karst cliffs and narrow gorges like Peñas Juntas to broad alpine meadows. The valleys fall within the protected boundaries of Las Ubiñas-La Mesa Biosphere Reserve and Somiedo Natural Park, providing an ecological refuge of native oak, beech, and chestnut woods. This untouched wilderness serves as one of the primary natural strongholds for the endangered Cantabrian brown bear, alongside Iberian wolves, chamois, and wild boars.

The Senda del Oso greenway follows the natural contours carved out by the Trubia and Teverga rivers. Spanning over 50 kilometers, the path tracks gently through rock tunnels and across river bridges, surrounded by steep mountain walls. Beyond the main valley floor, the surrounding mountain passes climb sharply into high-altitude terrain, featuring challenging ascents up Puerto de Ventana and Puerto de San Lorenzo, where cyclists face sustained gradients surrounded by panoramic views of the Cantabrian crests.