A converted mining railway track through Asturian valleys passing bear sanctuaries where rescued Cantabrian bears live in semi-wild enclosures. Beautiful green valley scenery through chestnut and oak forests.
The Senda del Oso (Bear Trail) follows a former narrow-gauge mining railway through the valleys of the Trubia and Quiros rivers in central Asturias, northern Spain. The 22-kilometre trail runs one way from Entrago in the Trubia valley to Tunon, threading through a succession of limestone gorges, chestnut oak forests, and traditional Asturian villages on a flat, converted railway bed.
The trail is named for the Cantabrian brown bear, a critically endangered subspecies that once ranged widely across northern Spain. Two semi-wild enclosures along the route — at Proaza and Teverga — house rescued bears that can be observed at close range from viewing platforms free of charge. The Cantabrian brown bear population has rebounded from fewer than 30 individuals in the 1990s to over 350 today across the Cantabrian Mountains, and this trail serves as an important wildlife education corridor.
The converted railway bed provides a remarkably flat, wide, and well-surfaced path — gravelled and compacted throughout — suitable for walking, cycling, and pushchair use over most of its length. The route passes through a series of dramatic limestone gorges, most notably the Garganta del Trubia near Proaza, where the river has carved cliffs 200 metres high. Two railway tunnels, each approximately 300 metres long and unlit, punctuate the route; a headlamp or torch is needed inside. Both tunnels can be bypassed via the adjacent road if preferred.
Trailhead access is straightforward: Entrago is reached by Alsa bus service from Oviedo (approximately 1 hour), and Tunon is similarly connected. Most walkers or cyclists cover the route one way and return by bus. Parking is available in both Entrago and Tunon, and at intermediate access points in Proaza and Teverga. Bike hire is available in Oviedo and Proaza.
The surrounding valleys receive high Asturian rainfall, keeping the vegetation lush and vivid green year-round. This also means the path surface can be muddy in wet weather, particularly in the gorge sections. The bear observation platforms at Proaza and Teverga are free to use and accessible; nearby, the Parque de la Prehistoria in Teverga offers cave art exhibitions as a complementary attraction.
Trail facts
- Trail area
- Asturias
- Best season
- April to October, walkable year-round in mild weather
Highlights
- Cantabrian bear observation
- Narrow gorge sections
- Medieval bridges
- Traditional Asturian villages
Tips for visiting
- Carry a headlamp or torch for the two unlit tunnels — natural light does not penetrate to the midpoint and the interior can be cold even in summer.
- Confirm the bear enclosure hours at Proaza and Teverga before setting out; opening times vary seasonally and can differ from general park hours.
- A bicycle makes the 22km one-way trip far more comfortable; bikes can be hired in Oviedo or Proaza and returned at the end point.
- The path surface becomes muddy after rain; waterproof trail shoes are recommended over road trainers.
- Asturias is one of Spain's wettest regions — carry a waterproof layer regardless of the morning forecast.
- The gorge section near Proaza is the most spectacular; those with limited time can walk the 6km section from Proaza to the bear enclosure and back as a satisfying short outing.
When to visit
April through October offers the most pleasant walking conditions. Spring (April to May) brings vivid green valley scenery and strong waterfall flow; autumn (October) delivers chestnut and oak colour. The route is walkable year-round in milder weather, though winter rain can make gorge sections very muddy.
Accessibility
The Senda del Oso is one of Asturias's most accessible long trails. The flat, compacted railway-bed surface is suitable for wheelchairs and pushchairs along most of the route. The two unlit tunnels can be bypassed via the adjacent road. The bear observation platforms at Proaza and Teverga are accessible. Some sections near the gorge become muddy and uneven in wet weather, limiting wheelchair accessibility in those areas.
Frequently asked questions
Can Cantabrian brown bears be reliably seen on the Senda del Oso?
Yes, with reasonable certainty. The two enclosures at Proaza and Teverga house rescued bears in large, semi-wild enclosures that visitors observe from platforms. Wild bears from the broader population very occasionally enter the valley corridor, but encounters with wild bears on the trail itself are rare.
Is the Senda del Oso suitable for cyclists?
Yes. The flat, wide railway-bed surface makes the trail one of Asturias's best cycling routes. Bike hire is available in Oviedo and Proaza. The route is suitable for standard hybrid bikes; mountain bikes are not required. The two tunnels require lights for safe navigation.
Is there an entrance fee for the bear enclosures?
The bear observation platforms at Proaza and Teverga are free to visit. The nearby Parque de la Prehistoria (Teverga) charges a separate admission for its prehistoric art exhibitions, but this is not required to see the bears.
How is the Senda del Oso accessed by public transport?
Alsa bus services run from Oviedo to Entrago and to Tunon, making a car-free one-way trip viable. Connections operate approximately four times daily; current timetables are available on the Alsa website.
Is the trail suitable for pushchairs and young children?
Most of the route is pushchair-friendly on its flat, compacted surface, with the exception of the two unlit tunnels (easily bypassed via the road) and a few muddy sections near the gorge. The bear observation platforms are accessible to pushchairs, making this an excellent family outing for children of all ages.