From the northern coast to the mountains rising to 1500 metres in the south, Gipuzkoa afforded these people a relatively varied relief. Three principal rivers - the Oria, the Urola and the Deba - flowed northward across the territory, forming valleys which were to become important communication routes. A series of smaller intermediary valleys further divided up the space, offering a variety of elevations and environments.
The local climate of the first millennium BCE was not significantly different to our own, albeit somewhat colder: winters were mild and wet and even the highest peaks remained free of snow for much of the season; typically of a temperate oceanic climate without a dry season, summers were cool.
The mild temperatures in the low valleys and the relative lack of frost, together with frequent rainfall, heavier in mountain areas, resulted in abundant vegetation, with large stretches of forest.
The human impact on the environment was greater than in earlier times, especially in areas closest to the settlements. The original oak groves gradually made way to bushes and grassland, ferns, and a range of plants and trees related in one way or another to human occupation.