Selva de Oza: 7 hiking routes in the Aragonese Pyrenees

As soon as you pass the Boca del Infierno, the valley opens and the air changes: it smells of moss, wet bark and beech. The Selva de Oza, in the Hecho Valley, feels like stepping into a Pyrenees that still moves at its own pace.

It is part of the Western Valleys Natural Park. Here the Aragon Subordán River runs between meadows and walls of reddish rock, and the trails leave from a single point at every level of difficulty.

The best thing about this place is that you don’t have to be a mountaineer to enjoy it. There are morning walks beside the river and long climbs up to ibones, and the light between the beeches at first hour is reason enough for the trip.

I have chosen seven routes, from the gentlest to the toughest, so that you can decide realistically. All the distance and elevation figures are approximate, because they change with the GPS track and the starting point.

1 Aguas Tuertas Valley: the easiest route

You set off from the Guarrinza car park, which has room for about 40 cars. A gravel track climbs about 3 km to a cattle gate and the Aguas Tuertas refuge.

About 50 metres from the refuge, on the left, stands the Aguas Tuertas dolmen, a witness to human presence in prehistoric times. The river draws slow meanders across an alpine meadow, which is why it has that name.

With about 6 km in total and an easy grade, it is an outing for children or for a relaxed pace.

It is also a good first contact to learn how you respond at altitude: if you have energy to spare on reaching the refuge, you have the answer for deciding the next outing (and yes, sometimes the best plan is to repeat this one).

2 The Roman Road: forest and remains

It is a circular route that follows the line of the old Roman road, through forest and shade. Be careful: guides warn that it is not for everyone because of its climb.

Choose it if you like mixing landscape and heritage, and not if you want a flat Sunday stroll.

3 Ibón de Acherito: the glacial lake

Ibón de Acherito, at 1,880 metres, is one of the most visited in the Aragonese Pyrenees. The route figures vary a lot depending on the source (between 10 and 14 km round trip, and between 650 and 800 m of positive elevation), so plan for a whole day.

It is worth the effort because the lake sits boxed in between limestone ridges. Go up with enough water and a plan B in case the weather changes.

Arrive with time in hand: the way back feels long, and the climb is felt more in the legs than on the map.

4 Ibón de Estanés: further away, with a different reward

The path to Estanés (about 1,777 m) shares the first stretch with the one to Aguas Tuertas and then branches off. Depending on the stretch chosen, the route runs from 12 to 16 km.

It is a long outing and real mountain terrain. Start early and check the condition of the trail beforehand.

5 Peña Forca via the Estribiella ravine

One of the departures starts at the “Estribiella-Peña Forca” sign, next to the first house in the area and before the bridge. The first stretch, along the Estribiella ravine, is shared with other ascents in the area.

From the meadow you get views of the Peña Forca and Rincón de Alano massifs. This route demands more orientation skills and more experience, and should not be improvised.

6 Castillo d’Acher: the area’s challenge

The Castillo d’Acher, at about 2,384 m, is the reddish silhouette that dominates the valley and one of the most sought-after summits. It is considered a moderate to demanding ascent, of about 14 km.

It is only for those with stamina and good conditions. In the changeable weather of the mountains, caution is part of the route.

7 The entrance: Boca del Infierno

Before reaching Oza, the road passes through the Boca del Infierno, the ravine through which the river makes its way. It is not a route in itself, but it is the best way to start the day, with the water sounding a few metres away.

If you have time, stop at a lay-by and watch how the landscape changes: from closed rock to open valley.

On the way back, in the afternoon light, the same stretch seems like another place. Go through it twice.

Tips for planning your walk in the Selva de Oza

• Weather: check the forecast the day before. In the high mountains, clouds arrive fast.
• Signal: it is scarce in the valley. Download the map and the GPS track for offline use.
• Signposting: the main trails are marked (the GR-11 passes through the area), but it is best not to rely only on the signs.
• Footwear: a sole with grip, because the humidity of the forest leaves roots and stones slippery.
• Layers: bring a windproof garment even if you set out in sunshine.
• Pace: the long routes are best enjoyed by setting out early.
• Water and food: always carry them, because on the long routes there is nowhere to restock.

Which Selva de Oza trail appeals to you most: the short walk to the dolmen or Ibón de Acherito?