The canyon of the Arnoia river Nature · Arnoia, Ribeiro, Ourense Image of Arnoia, not of the place itself. Before giving itself over to the Miño, the Arnoia cuts into a gorge with steep walls where it forms narrows and small waterfalls. It is the wildest corner of a concello that barely rises above eighty metres of altitude in its lowlands. At 84.5 kilometres, it is the longest river in the province of Ourense; it rises in the concello of Vilar de Barrio, in the Sierra de San Mamede, and crosses Baños de Molgas, Xunqueira de Ambía, Allariz, A Merca and Celanova before marking the boundary between Ramirás and Gomesende to the north and Cartelle and Cortegada to the south, cut into a canyon with a 300-metre drop over seven kilometres, among crags and woodlands. Already within the concello of Arnoia it forms the valleys of San Vicente and San Amaro before flowing into the Miño, at Portocarreiro, opposite a granite islet. Photo: Luis Miguel Bugallo Sánchez (User:Lmbuga) (CC BY 3.0) What to see and do in Arnoia