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 small town of Oronoz-Mugairi (municipality of
Baztan) in the province of
Navarre, the river actually results from the merge of several streams near the village
Erratzu, with the stream
Baztan that rises at the north-eastern side of the mount
Autza (1,306 m) being considered the source of the
Bidasoa. It joins the
Cantabrian Sea (
Bay of Biscay) between the towns of
Hendaye and
Hondarribia.