Aydius is a French commune in the Pyrénées-Atlantiques department in the Aquitaine region of south-western France.
Aydius is located some 25 km south by south-east of Oloron-Sainte-Marie just east of Bedous. Access to the commune is by the D237 road from Bedous which goes to the village and terminates there. The commune is alpine in nature with extensive forests, rugged terrain and snow-capped mountains in the east.
The Gabarret river rises in the east of the commune and flows west gathering a large number of tributaries including the Ruisseau d'Arces, the Ruisseau du Saslars, the Gave de Béranfueil, the Gave de Bouren, the Ruisseau d'Ilhiec, the Ruisseau Sarité, the Ruisseau de Traillère, and the Ruisseau de Sahun (which forms part of the western border of the commune) before flowing west to join the Gave d'Aspe at Bedous.