One of the main characteristics of this region is the rough slopes, with very steep mountainsides that are linked across by narrow and deep valleys, through which the rivers Lea and Artibai and their tributaries run.
The name of the Lea Artibai region is taken from its two rivers, which shapes the region into two valleys. The rivers and valleys are formed in the south, from the mountain range in the natural park in Urikola, and serve to connect to the west with the biosphere reserve in Urdaibai. These rivers have a basin that has not changed much and that is preserved in a magnificent state, with good reason Lea is considered one of the cleanest coasts in the Basque Country. In the upper sections, where the banks are well preserved, alders, ashes, oaks, and hazelnut trees grow. Aquatic vegetation is very abundant and diverse in the basin, since there are numerous dams and reservoirs that transform the rivers in some sections into small ponds or pools, thus alternating with areas of rapids.
This region has been successful in maintaining its ancestral costumes and rural life style throughout the generations, which continue in the diverse farmhouses throughout its geographical landscape. With the emergence of blacksmithing activities the wooded forest landscapes gave place to pastures and orchards, which are very typical. Nonetheless, even today we can find enclaves of Cantabrian oak groves, with its characteristic flora of strawberries, bay leaves, climbing plants such as sarsaparilla or rubia peregrina, reforestations of oaks, chestnuts, beech trees, hawthorns, hazelnuts, as well as heather and whin.
The importance that some of these forests have played throughout the centuries can be seen in the stones used in the farmhouses; a faithful reflection of that is the characteristic sandstone used in the farmhouses surrounding the forest of Oiz, and the famous marble from Markina-Xemein taken from their quarries.
In order to obtain an excellent view of the interior land and coast there’s nothing better than to climb the forests of Kalamua, Lluntzar and Oiz. The latter is the highest one in the region and has the youngest forest in Bizkaia; it is one of the 5 Hornblower Mounts in Bizkaia, from where the Gernika Committee was summoned to the General Council and to send emergency alerts to the province. Currently it can be seen practically from the entire region, given the windmill park that is located at the summit.