The Eo is a river, 91 kilometres (57 mi) long, in northwestern Spain. Its estuary forms the boundary between the regions of Galicia and Asturias. The river is known for its salmon fishing.
In the western Cantabrian mountains the river forms the axis of one of Asturias 7 biosphere reserves, the Eo river, Oscos and Terras de Burón Biosphere Reserve.[2]
43°33′02″N 7°01′52″W / 43.5505°N 7.0311°W / 43.5505; -7.0311