The starting point is the car park area at kilometre 5 of the track leading up to Belsué reservoir from the Apiés - Sabayés road. From this carpark a path strikes out to the right, leading in a south-easterly direction straight towards the Peña de San Miguel. This crag can be skirted either to the left or the right or we can also climb up to the top, scaling metal stairs that call for a certain prudence. At the top there are the remains of diverse Roman constructions and stunning views of this part of the Sierra de Guara, with the Peña de Amán looming large in the foreground.

To do the second part of the proposed route, the descent to the River Flumen, we need first to return to the car park to take the road leading to the northeast (to the left as you come from the Sabayés track). The descent to the river is a little over one kilometre and runs through Kermes Oak scrub and scree slopes. The drop down to the river, despite the downward slope, takes about half an hour. There is no chance of getting lost if we stick to the wide track, which first of all passes a farrowing pen, then a hut and later through the poplar carr of the springs of Lavallos, eventually reaching the river through the old vegetable gardens of Santolarieta. The return to the carpark is a stiff climb and takes about 45 minutes, double the time normally taken on the walk down.

The Sierra de Guara has an unquestionable ecological importance. Birdlife is particularly rich with a high density of raptors and such valuable species as the Lammergeier, which can often be seen soaring in the sky or around the cliffs of this part of the Sierra. Griffon Vultures, Egyptian Vultures and Peregrine Falcons are other birds of prey that might be spotted here. What this Sierra is best known for, however, is as an unrivalled open-air school for the sport of gorge descents.