The Adour (French pronunciation: [aduʁ] ^ⓘ; Basque: Aturri; Occitan: Ador) is a river in southwestern France. It rises in High-Bigorre (Pyrenees), in the commune of Aspin-Aure, and flows into the Atlantic Ocean (Bay of Biscay) near Bayonne. It is 308.3 kilometres (191.6 mi) long,^[1] of which the uppermost ca. 11 kilometres (6.8 mi) is known as the Adour de Payolle. At its final stretch, i.e. on its way through Bayonne and a short extent upstream, the river draws the border between the Northern Basque Country and Landes regions.

Départements and towns along the river include:

• Hautes-Pyrénées: Bagnères-de-Bigorre, Tarbes, Maubourguet
• Gers: Riscle
• Landes: Aire-sur-l'Adour, Dax, Tarnos
• Pyrénées-Atlantiques: Bayonne

The main tributaries of the Adour are, from source to mouth:^[1]

• Adour de Gripp (also Adour du Tourmalet, 15 km)
• Adour de Lesponne (19 km)
• Échez (64 km)
• Arros (130 km)
• Léez (56 km)
• Gabas (117 km)
• Midouze (151 km)
• Louts (86 km)
• Luy (154 km)
• Gave de Pau (191 km)
• Bidouze (82 km)
• Aran (48 km)
• Ardanabia (26 km)
• Nive (79 km)

• Commission Européenne—Natura 2000: Cartographie du Barthes de l'Adour—(in French) — maps of the Adour and Adour Basin.
• Natura 2000 Sites d'Intérêt Communautaire par la France: Barthes de l'Adour — (in French)
• Adour Archived 2014-11-10 at the Wayback Machine—(in French) — website homepage.
• European Commission: official Natura 2000 Network website— — "the centrepiece of EU nature & biodiversity policy."