The Nervion, one of the most famous of the Basque Country rivers due to its spectacular estuary, rises among the beech forests of the Sierra de Gibijo near the port of Orduña. The water falls vertically from a height of 200 metres, a natural display that is only seen in times of rain or melting snow.

The salto de Nervion (the Nervion leap) can be viewed with ease from an awe-inspiring lookout point at the top of the waterfall. It can also be reached via the Delika gorge, after crossing the beech forest, although this is a more difficult route, and when the river is high it is impossible to avoid getting your feet wet.