The mountain range includes the highest peaks in the Basque Country Region: Aitzuri, at 1551 metres, and Mount Aizkorri, at 1528 metres. The impressive massif is a privileged place to contemplate both the south of Guipuzkoa and another different landscape, that of the Alavesa plain.
The three main Guipuzkoa rivers, the Oria, the Urola and the Deba, spring from amongst the rocks of this large wall of limey ridges which marks the south of Guipuzkoa. A wall which, nevertheless, has been crossed by man since ancient times. Proof of this can be found in the multiple megalithic monuments and the tunnel of San Adrián, a split-open rock through which pilgrims on the Road to Santiago passed from Guipuzkoa to Alava. The basilica of Arantzazu is another significant example of human intervention in this splendid natural area.
Flora and fauna
The peregrine falcon, the Griffon vulture, the wild cat, the marten and the Alpine newt are important representatives of the fauna of Aizkorri. Not far away we find typical examples of Latxa sheep. With regards to flora, the beech groves and oak woods give way to interesting mountain species.
From Oñati take the main road to Arantzazu. It can also be reached from Zegama (Alto de Otzaurte) and from Urkulu Reservoir in Aretxabaleta. Take the N-1 exit junction in Idiazabal, and then take the GI-2637 heading towards Segura and then Zegama.