This is the classical route of SW face.
Trailhead: col of Aritxulegi (450m), after the tunnel in the road between Oiartzun and Lesaka.
Just over the road the path begin over the tunnel. It's a little path among grassy hills to get the terraces with fences. Under the bottom of Erroilbide we'll turn directly to this peak (right-west). Just in the bottom we'll turn to get a little path to north side (left) bordering the peak to get the grassy channel (hard slope), and the easy rock-climb (I, grade F.) to reach a col near of the fisrt summit, the Erroilbide (836m)
After a descent of a wall of rock (I+) we'll reach the most complicated section of all the route, it's the access to Txurrumurru. The south side (our access in this moment) is grade II for 20 meters with good rock, it's impressive but not difficult. The first section (II) had a metallic anchorage ("anilla") and the second section is a wide chimney (II). The final section is the easiest (I, F). In the summit of Txurrumurru (826m)
the descent is easy across the north side (I). In the little col the access is a simple walk-up to the last peak, Irumugarrieta (810m)
Generally, if you don't have 2 cars, you must descent to Elurretxe (north) and take the little path under the peaks in south direction (under the east face of peaks) to return to Aritxulegi across the GR with paint white and red.
Rope?, not generally, only for beginners or in days with rain or fog (wet rock).
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