The Barthes de l'Adour are vast floodplains located on either side of the Adour river and its tributary Le Luy. Wetlands formed by man and nature, it is of major ecological interest in France and in Europe justifying it being listed in a Natura 2000 zone. Nature lovers can observe a remarkable variety of species: European pond turtles, otters, storks, egrets, water clover, estuary angelica, etc.

In Pays d'Orthe & Arrigans, the Barthes are accessible from Port-de-Lanne, Saint Etienne d'Orthe, Pey and Orist.