The Urdaibai estuary is a significant natural area located in the Basque Country of Spain. It is characterized by its rich biodiversity and unique ecosystems, including wetlands, marshes, and coastal habitats. The estuary is home to various species of birds and marine life, making it an important site for conservation and ecological studies. Designated as a Biosphere Reserve by UNESCO in 1984, the Urdaibai estuary plays a crucial role in the local environment and economy. It supports fishing, tourism, and agriculture, while also providing recreational opportunities for visitors. The surrounding landscape features picturesque villages and stunning views of the Basque coastline.