Yera and Aján Riverbanks Trail

This trail is considered a moderate run, requiring a good level of fitness. While some sections are relatively flat and suitable for various skill levels, the overall route demands a reasonable physical condition for jogging. It's a great option if you're looking for a moderately challenging experience.

The route features a varied terrain. You'll find a mix of surfaces, including some paved sections, but a significant portion consists of unpaved compacted soil and white gravel paths. Be prepared for potential mud and water, especially within the tunnels, so sturdy footwear is recommended. Parts of the trail follow the old Santander-Mediterranean railway line, offering relatively flat stretches.

This trail offers a blend of natural beauty and historical intrigue. Key highlights include the scenic Aján River Waterfalls, the impressive Engaña Tunnel (which you can explore from its accessible ends), and the fascinating Yera ghost station, an abandoned railway landmark. You'll also see stone bridges, dense forests, and green meadows.

No, the Engaña Tunnel, while a major highlight, is not fully passable for its entire length. It's nearly 7 kilometers long but has been largely collapsed and completely blocked since 1999, particularly around the 2,800-meter mark. You can explore sections from either end, but you cannot run through its entirety.

While specific parking areas are not detailed, access points to the trail, particularly near the Engaña Tunnel or the Yera ghost station, typically offer informal parking. It's advisable to check local maps or community forums for the most convenient and designated parking spots near the trailhead before your visit.

Generally, trails in this region are dog-friendly, but it's always best to keep your dog on a leash to ensure their safety and respect local wildlife and other trail users. Given the varied terrain and potential for mud, ensure your dog is comfortable with such conditions.

The best time to run this trail is typically during spring, early summer, and autumn when the weather is milder and the natural scenery is at its most vibrant. During winter, be prepared for colder temperatures, potential snow, and increased mud, especially within the tunnel sections.

No, you do not need any specific permits or have to pay an entrance fee to access the Túnel de la Engaña – running circular on the Aján trail or the surrounding Valles Pasiegos area. It's freely accessible for public enjoyment.

Yes, the route incorporates sections of several other paths. You'll find yourself running along parts of the Ferrocarril Santander-Mediterráneo, and it also passes through shorter segments of the [CIMA CA05] Estacas de Trueba, Túnel de El Majoral, Túnel de El Morro, Túnel de El Empeñadiro, and Túnel de El Morrito.

The trail is located in a more natural and rural setting. While there might not be facilities directly at the trailhead, you can typically find cafes and restaurants in the nearby villages within the Pasiegos Valleys. It's a good idea to plan for refreshments before or after your run.

Given the moderate difficulty and varied terrain, wear comfortable running shoes with good grip, as you might encounter uneven surfaces and mud. Layers are advisable due to changing weather conditions, and a headlamp or flashlight is essential if you plan to explore the darker sections of the Engaña Tunnel. Don't forget water and snacks.