This route starts out from the village of Tarna, where you take a path to the right, paved with concrete in some sections, which heads uphill between stone walls to a beautiful beech forest. A little further on you come to a sharp bend to the left leading to the Terreros crossroads, where paths cross. At this point the trail branches into two: the left fork leads to Pyrenean oaks on Llano del Toro, and the right one to Tabayón Waterfall.
Taking the left fork, the trail continues for a fair stretch until reaching a small clearing, which you cross, climbing to the top. Further on, a narrow path leads into the woods, reaching Llanu'l Toru, as sort of hill in the middle of the beech wood.
From there you head back the same way to Terreros crossroads, where you now take what is the left fork leading to Mount Saperu. Further on, you cross Requexada Stream over a beautiful wooden bridge to walk in the shade of the trees without encountering any steep slopes.
A little further on, the track ends at Los Arellales Spring, while the route continues skirting the hillside to reach a clearing from where the peaks of Cuetu Negru and Cantu'l Osu can be seen. Shortly after, you come to the area of level ground called La Campona, from where you soon reach Tabayón Waterfall. Though not much water flows over it, this is a singularly beautiful waterfall due to the height of the leap and the majesty of the surrounding beech wood. Crossing the high meadow and heading slightly downhill, you come to the River Mongallu, which you ford wherever you are best able to.
The trail then heads back to La Campona, where you take a path that will allow you to close the loop, instead of having to backtrack.
To do so, you take a blazed path, though less evidently marked at the beginning than the one that brought you up here. This runs below the high meadow, leading into the River Mongallu Valley below the slopes of Cuetu Negru.
It soon becomes a wide path through the woods as it heads down into La Ablanosa Valley, where, in the middle of a small clearing in the woods - Majada Rebollau high meadow -, the trail turns sharply to the left, offering views of Cantu'l Osu. You cross the River Nalón over a sound bridge and the trail heads upwards for a short distance to reach the road to Tarna Pass. Just 20 metres further on, however, a path heads gently downhill to the right, between the river and the road. This path between farmland leads to the village of Tarna, coming out right at the entrance to the village, at the point where you began the route hours earlier.
