The Bidasoa is a river in the Basque Country of northern Spain and southern France that runs largely south to north. Named as such downstream of the village of Oronoz-Mugairi in the province of Navarre, the river actually results from the merger of several streams near the village Erratzu, with the stream Baztan that rises at the north-eastern side of the mount Autza being considered the source of the Bidasoa. It joins the Cantabrian Sea between the towns of Hendaye and Hondarribia.