Peñas de Aia / AiakoHarria Natural Park

The Aiako Harria Natural Park is located on the foothills of the Pyrenees, in the eastern part of the province of Guipúzcoa.

This granite massif of great ecological interest and outstanding beauty, is noted especially for its vast forests and varied fauna. There are a number of streams in the surrounding area such as the Aitzondo with its 100 m waterfall.

The Aiako Harria Natural Park is located on the foothills of the Pyrenees, in the eastern part of the province of Guipúzcoa. It includes a Palaeozoic massif containing outcrops of the oldest materials in the Basque Country. Eruptions of volcanic rock metamorphosised the Palaeozoic materials on the surface and today, erosion has revealed the vivid granite mass of Aiako Harria. This singular arrangement of layers of different materials represents one of the geological marvels of the Basque Country.

Aiako Harria comprises a series of narrow, steep-sided valleys, ravines and waterfalls. In spite of the fact that some areas of the Park are covered by conifer plantations, there are also stretches of natural forest such as the mixed forest of oak and beech of Añarbe, the forest of Pendulate and Pyrenean oak of Endara and the beech wood of Oianleku. In addition to these woods and forests, the most singular types of vegetation due to their biological interest are the small areas of sphagnum or peat moss, which grow between silica rocks, and communities of plants in protected areas close to small streams.

The fauna found on the Park corresponds basically to the Euro Siberian type. There are 147 species of vertebrates, the most important of which are forest species such as roe deer and wild boar, Griffin vultures that form colonies high up on the crags and cliffs, and aquatic animals such as salmon.

However, this area is characterised not only by natural formations but by the old mines that exist in the Park. The most important of these is the Roman mine of Arditurri. The remains of these industrial installations, dotted all over Aiako Harria, form a very peculiar landscape: Ventilation shafts, mine entrances, railways, etc. form part of this important historical and industrial heritage. This is also the case of the military fortifications, the Erlaitz fort and others, that also represent an important part of the history of the region.

On the other hand, there are abundant remains of prehistoric cultures: dolmens, burial mounds and especially cromlechs, evidence of the funeral rituals practised by the Neolithic peoples of this area. The great demand for recreational facilities has led to the creation of a large number of picnic areas in Aiako Harria, most of these with direct access from the main roads in the area.