Reaching the trailhead
The Guarrinza trailhead is placed about two kilometers upstream from the camping area of Selva de Oza, on the upper valley of the Aragón Subordán. To get there, start from Huesca or Pamplona, in northern Spain. From any one of both towns, follow road N-240 towards the other one. At Puente la Reina (88 km away from Pamplona, or 72 km away from Huesca) you will have to turn north by road A176. This is the road running alongside the river Aragón Subordán, entering the Valley of Hecho. Follow the A176 up to the village of Hecho (you might also find it written as "Echo"). After crossing Hecho the road becomes sensibly worst, but goes on to the Boca del Infierno (that's a narrow pass) and Selva de Oza. Keep going for an additional two to three kilometers on a worsening road. When the forest opens up and you the valley turns right (east), there's a tiny bridge over the river on your left side. Cross it to reach the grassy area where climbers usually park their cars.
Nearest spanish railway stations: Pamplona / Huesca
Nearest spanish airports: Pamplona / Zaragoza
A call for attention: in winter time, specially after heavy snowfall, the old camping site at Selva de Oza might be the place to leave your car, as the road is not cleaned any further north.
Road map by viamichelin.com
What you will find thereJust a dead-end of the road, and an ample grassy area where tents might have a place (though camping is officially forbidden, sorry about that). Also a couple of small rivers, coming down from the Barranco de Acherito and from the Aguas Tuertas valley, and the ruins of an old hut which used to serve as an advanced post for border guards ("carabineros") in the old times. Nothing else.
What to climb from Guarrinza - La MinaPeña Forca (2391 m)
Castillo de Acher (2390 m)
Acherito (2362 m)
Anzotiello (2211 m)
Chipeta Alto (2189 m)
An additional possibility for all publics, with no need to climb, is the nice uphill walk to the secluded Ibón (lake) de Acherito. Just a matter of a couple of hours to reach it.