Aizkorri-Aratz Natural Park has an area about 19,400 hectares, and includes the ridges corresponding to the Zaraia, Elgea, Urkilla, Aizkorri and Altzania mountain ranges which mark the division of waters between the Bay of Biscay and the Mediterranean. Three of the most important rivers in Gipuzkoa originate here: Deba, Urola and Oria.
Limestone is the predominant rock, and both the scenery and the shapes generated are some of the main features of the ridge. The circulation of subterranean waters has created an extensive network of underground galleries. Thus, the cultural heritage contained in Aizkorri-Aratz Natural Park is very important.
This vast terrain offers the possibility of visiting an important religious centre, namely, Arantzazu Sanctuary, as well as dolmes, and even ancient structures related to carbon mining and sheep herding.
Beech groves, oak groves, mountain grasslands and conifer woods cover most areas of Aizkorri-Aratz Natural Park. The variety contained in this natural space is very important, since there is a very interesting combination of mountain flora.
The diversity of ecosystems is reflected in the numerous species that inhabit the area: Alpine newt, Iberian frog, Peregrine falcon, Griffon vulture, Egyptian vulture, Alpine chough, Red-billed chough, European snow vole, marten, European polecat, Mountain cat, and several species of bats...
From the beginning of Spring to the end of the Autumn, thousands of sheep graze on the high meadows.
The origin of human presence in this environment goes back thousands of years. The most important pieces of evidence of mankind's presence in this area are dolmes. Sheep herding, carbon mining and other similar activities have also left their footprints in the area. Additionally there is the Arantzazu Sanctuary, a place where religion and culture meet. To top it off, Arrikrutz cave is an important addition to the cultural heritage of the area.