Urdaibai Biosphere Reserve with a dog

 This is a natural space of high environmental and cultural interest, declared Biosphere Reserve by UNESCO in 1984. It spreads over the hydrological basin of the Oka river, with a surface area of 220km2. Its heart and backbone is the estuary: the confluence of continental freshwater from the Oka river and the sea’s salt water. Discover Urdaibai with a dog, walking around its salt marshes, cliffs, beaches, fishing villages and spectacularly beautiful nooks.