The River Leitzaran zigzags down from Navarra to Andoain where it enters this valley, providing a habitat for many aquatic species and a wide variety of flora. The Plazaola rail trail also crosses the valley making this biotope ideal for a walk or a bike ride. The river and rail trail join up at the Otieta visitors’ centre. It has been designed as a recreation area, a fishing school and offers bike hire.