Apart from its extraordinary beauty, the massif stirs up great geological interest, since it is the only granite massif in the Basque Country. It is also the oldest land in the country, dating from the Primary or Paleozoic Era.
The massif boasts three main summits: Irumugarrieta (806 m), Txurrumurru (821 m) and Erroilbide (837 m), which are also known as Tres Coronas (Three Crowns), Las Batallas (The Battles) or Cara de Napoleón (Face of Napoleon). Varied signposted routes will lead us to those peaks. The most widely used route is over the Aritxulegi Saddle.
Peñas de Aia offers spectacular scenery: the coast with the Txingudi Bay in the foreground, which is a significant place in the migration paths of aquatic birds; the towns of Hondarribia (and its Old Town), Irún and Hendaye; Mount
Jaizkibel (and the sanctuary of Guadalupe); the Oiartzun Valley... The natural park also extends southwards, through a landscape of summits and passes (Aritxulegi, Bianditz, Aldura, Urdaburu) along the boundary with Navarre.
Going down Peñas de Aia, we will bump into streams that form tangled gullies, being Aiztondo, with a spectacular 100-metre waterfall, and Endara, which is surrounded by excellent oak groves, the most remarkable ones.
Veins of different metals have formed inside this rock massif of solidified magma. They have been exploited since very ancient times, some since the Roman Period, and the number of wells and mining galleries dotted over the massif can be counted in dozens. It has been calculated that there is a total tunnel length of about 15-18 km. In the old Arditurri Mines (Oiartzun) will be constructed an Interpretation Centre and a mining gallery will be adapted and opened to the public.
The promenade known as Vía verde de Arditurri goes through the former railway connecting the old mines with the Pasaia mountain pass. This 10km-long route is accessible for handicapped people, bikes and pedestrians.
The most common way to get up to the summits of Aiako Harria is from Pikoketa, leaving from the towns of Oiartzun or Irún. From Irún we can also get to Bianditz Pass, which is located at the centre of the natural park offering an excellent panoramic view. Besides, we encounter in an area rich in megalithic monuments. In fact, the same can be said of the whole zone, where over ten stone circles, seven dolmens and an occasional tumulus have been listed. In Aizpitarte, another part of the natural park, several caves accommodate important prehistoric sites.
Cycle line to the Arditurri Mines adapted to disabled people.
Camping is allowed in the area around the refuge of Arritxulo, although you have to ask for permission.
Organised activities: rock climbing, canyoning, hiking, biking, guided visits, etc.
- Sixteen recreational areas with refuge, tables, fountains, barbecues and other services.
- Nature workshops in Artikutza, Ibarla and Santiagomendi.