From the starting point, you first climb to the charming Ermita de la Virgen de la Antigua, offering beautiful views of the surrounding area. This small, whitewashed chapel is a tranquil haven in the landscape and is deeply rooted in local tradition. The route then follows the gentle course of the Estena River. What makes this hike so unique is the passage through the "Boquerón" (the "big mouth"), a spectacular ravine where the river carves its way through the quartzite rocks. Along the way, you'll pass the imposing Torres del Estena. These immense, vertical rock formations tower over the trail like natural watchtowers. They are a perfect example of the "Appalachian relief" that characterizes this area. The trail itself is relatively flat and leads you through lush vegetation of willows, alders, and ferns that contrast beautifully with the rugged, gray mountainsides. The Boquerón del Estena is world-renowned for its geological significance. As you walk, you walk on a seabed that is no less than 400 million years old.