The Acumuer Valley is one of the most undiscovered parts of the region and the Isín trail will take you there. It starts with a pleasant climb on a well paved track which brings you on to the GR 15. Staying with the GR 15, the next stage is a testing single-track trail as far as the River Aurín. There, you have to cross the river at the ford, obliging you to take off your shoes and socks, no matter what the season (in the spring time, please be aware of the volume of water). As you leave Isín, going down the road you took into the village, at the bottom of that section you take the track on the left and follow the signs. From there, the track climbs for a few kilometres, past a barrier, eventually arriving at a path that descends into the ravine of the River Aurín. You cross the ravine and carry your bike up the track, only a few metres! At that point, you will take to the road to return to Isín, leaving Acumuer village on your left.