The route utilizes tracks originally laid in the 19th century for the Asturian Mining Company.
The path connects four distinct councils: Santo Adriano, Proaza, Quirós, and Teverga.
The trail passes through an enclosure specifically designed to protect and rehabilitate rescued Cantabrian brown bears.
Several former train stations along the route have been preserved and converted into visitor service points or cafes.
Senda del Oso is a 22-kilometer former railway track converted into a paved greenway path through the Trubia River valley in Asturias. The route follows the path of an old mining train that once transported coal from the Quirós and Teverga mines. It features tunnels carved directly into the limestone rock and bridges crossing the river. The trail is shared by hikers and cyclists and is largely flat with a gentle incline towards the mountain villages. Near the Tuñón starting point, the path runs parallel to the river through dense hardwood forests. It serves as the primary gateway to the Somiedo Natural Park and Las Ubiñas-La Mesa Biosphere Reserve.
Inside the arched tunnels where the light creates a distinct contrast against the limestone walls.
Rent bicycles at the Tuñón trailhead to cover more distance than is possible on foot.
Carry a light jacket even in summer, as the tunnels and river valley remain significantly cooler than the surrounding area.
Check local weather forecasts specifically for the valley, as mountainous terrain causes rapid shifts in conditions.
Attempting the entire 22km path on foot without prior preparation; most casual visitors should pick a specific section.
Cyclists must yield to pedestrians; keep noise levels low to avoid disturbing local wildlife.
