Urdaibai Biosphere Reserve – Estuary Wetland, Coastal Hills, and Atlantic Wildlife

A UNESCO-designated landscape shaped by tide, migration, and maritime life

The Urdaibai Biosphere Reserve protects one of the most ecologically significant coastal landscapes in northern Spain, centred on the Oka River estuary as it meets the Bay of Biscay near Gernika and Mundaka. Saltmarsh, tidal flats, coastal hills, and fishing communities combine to form a landscape shaped by water, migration, and traditional land use. The final stages of the GR® 38 Wine & Fish Route approach the Atlantic through this protected estuary environment before reaching Bermeo.

This is a landscape defined by transition. River channels widen into tidal wetlands, mudflats and saltmarsh support migrating birdlife, and wooded hills rise above sheltered inlets. The interaction between freshwater, tide, and coastal weather creates constantly shifting light and atmosphere across the estuary.

Despite its ecological significance, Urdaibai remains a lived landscape. Fishing villages, small farms, and historic settlements sit alongside protected habitats, reflecting a long relationship between people and the estuary environment. Gernika-Lumo provides cultural and historical context within a landscape shaped equally by nature and community.

Walking here is defined by openness and quiet movement. Estuary paths, coastal routes, and hillside trails offer wide views across wetlands and tidal channels, while birdlife and changing water levels create a sense of continual motion within the landscape.

Beyond walking, the reserve is internationally recognised for wildlife. Migratory birds gather in large numbers, coastal habitats support diverse species, and tidal ecosystems provide essential breeding and feeding grounds.

Whether arriving from inland valleys or exploring the estuary’s quiet margins, Urdaibai offers one of the Basque Country’s most distinctive coastal environments.

About the UNESCO Biosphere Reserve

Urdaibai was designated a UNESCO Biosphere Reserve in 1984 in recognition of its ecological importance and the balance between conservation and sustainable human activity. The reserve protects wetlands, estuary habitats, coastal ecosystems, and traditional land use practices.

Where to Walk and Explore

GR® 38 Wine & Fish Route – Coastal Approach

‍The final stages descend through valleys and wetlands toward the Atlantic coast.

Estuary & Marsh Paths

‍Routes through tidal landscapes and bird habitats near Gernika and Mundaka.

Coastal Hills & Viewpoints

‍Trails offering elevated views across the estuary and Bay of Biscay.

Highlights

• UNESCO-designated biosphere reserve
• Tidal wetlands and migratory bird habitats
• Estuary landscapes shaped by river and sea
• Fishing communities and maritime heritage
• Quiet coastal walking routes and viewpoints
• Strong transition from inland valleys to ocean coast