Río Eo, Oscos y Terras de Burón Biosphere Reserve Nature · Santa Eulalia de Oscos, Eo-Navia, Asturias Image of Santa Eulalia de Oscos, not of the place itself. Biosphere reserve declared by Unesco on 19 September 2007, spanning 1,595.89 square kilometres across seven Asturian municipalities, including Castropol, Vegadeo, Taramundi, Villanueva de Oscos, Santa Eulalia de Oscos and San Martín de Oscos, and seven municipalities in the province of Lugo, such as Ribadeo, Trabada, A Pontenova, A Fonsagrada and Negueira de Muñiz. It comprises the entire basin of the river Eo, from its source at Fonteo to its mouth at the Ribadeo ria, the ria itself and part of the neighbouring basins of the Miño, Navia and Porcía, forming a unit of biodiversity, culture and heritage. When it was declared it had around 33,000 inhabitants, and since then almost all of its municipalities have been losing population. Photo: Bifus (CC BY-SA 3.0) What to see and do in Santa Eulalia de Oscos