The Ibaizabal region. The Ibaizabal basin is the largest natural region in Bizkaia. Its broad headwaters are the Duranguesado with the ridges of Udala, Anboto, Alluitz, Mugarra, etc., on the borders of Gipuzkoa and Alava. The area of Elorrio, Abadiano and the valley of Atxondo collects streams of water up to the great contribution of Mañaria, which collects the whole of the Rinconada as far as Urkiola. From Durango downwards, after receiving the streams from the Zaldibar and Bérriz area, the Ibaizabal becomes large. Then the Oiz and Bizkargui mountains, the corner of Arratia and other small valleys, round off the great basin of the Ibaizabal which continues its course through the centre of Bizkaia, Amorebieta, Galdácano, Ariz-Basauri and Bilbao. In Ariz it has received the Nervión, which has stolen its name from here. In the graphics of old Bilbao you can read the sonorous and Biscayan Ibaizabal in its place. The great basin of the Ibaizabal, the cradle of Biscay, includes the Encartaciones (except Somorrostro), and the whole region of the Nervión, from Basauri and Arrigorriaga to Llodio (A), Amurrio (A) and the plain of Orduña (V). This would be the large region of Ibaizabal as a whole, including the land of Ayala (A), which is geographically Cantabrian. The inhabitants of the industrial area of Bilbao have their natural outlet to the sea and the series of beaches from Las Arenas to Arminza for recreation. To their left, the whole Encartaciones area with its mountains and valleys. Following the Nervión, you will soon find yourself in the great Alava park that is the Ayala Valley. There you will find vast horizons of hills and valleys, cheerful streams, small villages and welcoming little valleys. Passing through Amurrio, you can reach the great fertile plain of Orduña and the villages of the Arrastaria valley (A). On the road ahead, you can climb up to the Orduña pass and from there you will be able to contemplate a wide panorama.