At the head of the Roncal Valley is the Larra massif, a spectacular landscape that nature has carved out of a mass of limestone rock. The massif rises to more than 2,000 m and its upper part is relatively flat, so you can enjoy breathtaking views of its surroundings. Its highest point is the Anie Peak, 2,500 m high.
Among the limestone pavement rocks of the massif, the black pines in the upper parts are notable. There is a mass of pine trees declared as the Ukerdi Integral Reserve, and another in the lower area, the Aztaparreta Ravine Integral Reserve, which protects a beech and fir tree forest.
The upper part of the massif holds an intricate network of galleries of more than 125 km, opened up by the action of the water, with some of the deepest chasms in the world, such as the San Martín chasm and the Illamina pass chasm.