The Petit-Rhône is an arm of the Rhône delta which marks the administrative boundary between the Provence-Alpes-Côte d'Azur and Occitanie regions, between the departments of Bouches-du-Rhône and Gard, and more symbolically between the Camargue gardoise and the great Camargue. It separates from the Grand Rhone north of Arles to reach the Mediterranean Sea near Saintes-Maries-de-la-Mer. The Petit-Rhône is recognized as an important site for the recovery of migratory fish.