History of the Bear Trail: from 1884 mining railway to greenway

It all started with a dream too big to be built. In 1860 Belgian engineer Gabriel Hein designed a railway that would cross the Cantabrian mountains via the Puerto de Ventana pass to connect Asturias with central Spain. But Bernardo Tiburcio Terrero, a powerful local landowner, did not want locomotive smoke drifting over his estates and blocked the full-gauge line. Hein was only granted permission for a 750 mm narrow-gauge track with a humbler purpose: hauling coal and iron ore from the Trubia valleys to the Trubia Arms Factory and the coastal blast furnaces.

The result was, unknowingly, a railway milestone. In 1884 Spain's first 750 mm gauge line opened: roughly 30 km between Trubia and Santa Marina de Quiros, with 12 tunnels and 7 bridges carved through impossible limestone gorges and river canyons.

In 1902 the Teverga branch was added, running from Santianes to Perihuela (Proaza) and creating the Y-shaped fork you can see on the trail map today. For sixty years the railway was the heartbeat of these valleys: it shipped out coal, brought in supplies and connected villages that would otherwise be cut off every winter.

On 15 October 1963 the last train made its final run. The road had won. The rails were lifted, the tunnels sealed and the bridges slowly disappeared under vegetation. The track lay dead for nearly three decades.

The second life of this railway began with a group of cyclists from Gijon. In the late 1980s they were riding back roads when they stumbled on the old trackbed: flat, traffic-free and with stunning scenery. They took the idea to the government of the Principality of Asturias and proposed turning it into a greenway.

The idea stuck. In 1991 construction began under the official name Senda Verde de los Valles del Trubia, backed by the regional government and the Mancomunidad de los Valles del Trubia. The project respected the original alignment: tunnels were kept, bridges rehabilitated and the surface paved for cyclists and pedestrians.

In May 1995 the first section, Tunon to Proaza (~6 km), opened to the public and the response was immediate. The Teverga branch (Proaza-Entrago) followed in 1996, and in 1999 the Quiros branch (Caranga-Valdemurio) completed the trail. The Bear Trail had reached its current layout: over 30 km with two arms splitting from the same junction.

In 1989 poachers killed a mother bear in the mountains of southwestern Asturias. Her two cubs, Paca and Tola, were rescued and taken in by the Fundacion Oso de Asturias (FOA), officially established on 30 October 1992. In 1996 the bears moved to a purpose-built enclosure at Monte Fernanchin beside the trail, and they quickly became the symbol of Cantabrian brown bear conservation.

Tola died in January 2018, aged 28-29. Paca was euthanized on 10 April 2025. In December 2013 a lone cub named Molina had been rescued, and today she is the only Cantabrian brown bear in captivity. She lives in the Monte Fernanchin enclosure, visible from the trail between Proaza and Tunon.

The bears transformed the trail from a cycling route into a nature experience. For many visitors, stopping at the viewpoint to watch Molina is the moment they remember most.

The trail preserves more original railway infrastructure than any other path in Asturias. Over 20 tunnels survive (from the main line and the Teverga branch), all lit and fully passable. Eleven rehabilitated bridges span the Trubia river and its tributaries, some still carrying their original 19th-century metalwork.

The route passes through the gorges of Penas Juntas and Valdecerezales, two limestone canyons that could only be crossed with tunnels and cantilevered bridges. Today those stretches are the most photographed sections of the entire trail.

And if you want to see one of the machines that once ran these tracks, the F.M. 102 locomotive, built in 1881 and the oldest surviving 750 mm gauge engine in Spain, is preserved in Asturias.