The Natural Park of Peñas de Aya (Aiako Harria) covers a total of 6,913 hectares of land in the easternmost part of Guipúzcoa, in the foothills of the Pyrenees, in part bordering Spain and France. It includes part of the municipalities of Irún, San Sebastián, Oiartzun, Rentería and Hernani.
The territory of the park expands between the channels of the Bidasoa and Urumea rivers and it has its most visible face in the massif of Tres Coronas, – a great granitic elevation (the only one in the province) formed by the mountains Irumugarrieta, Txurrumurru and Erroilbide, which with its 837 meters of height also supposes its roof. The rest of Peñas de Aya has an irregular relief of great ecological value formed by deep valleys with a large number of ravines and waterfalls. Water is one of the main values of the place, the Añorbe reservoir or the waterfall of Aiztondo are great examples the latter being the largest in the Basque Country thanks to its 100 meters of free fall. The peaks of Peñas de Aya, afford remarkable views that extend from Txingudi Bay to Mount Jaizkibel or the Oiartzun Valley .
The predominant forest mass of the park of Peñas de Aya is composed of beeches or oaks. You can also find some endemisms such as soldanella villosa. Its skies are furrowed by birds such as the griffon vulture, the Egyptian vulture or the golden eagle; as to the fauna of Peñas de Aya, it includes wild boars, roe deer and foxes. The Endara River is a regular spawning place for salmon
Peñas de Aya is a usual place for active tourism enthusiasts, because it is a more than appropriate space to practice mountaineering, hiking or bicycle tours, thanks to the extensive network of signaled trails that crosses its lands. It also has an exceptional cultural value in the mines of Arditurri, that review a mining tradition that began to develop in Roman times.
Access:To enter the park of the Peñas de Aya, the most usual is by the GI-3454 road, which connects Irún with Oiartzun, or by the GI-3420, between Oiartzun and Lesaka. The park has several resting areas with their own parking.