Ars-en-Ré is one of 10 communes located on the Île de Ré off the coast of La Rochelle and is in the north-western part of the island some 8 km west of Saint-Martin-de-Ré.
Its harbour is the largest on the Ile de Ré and is located at the bottom of the Fier d'Ars (a body of water penetrating the land from the north-east and bordered by marshes), which is reached by a channel through the Salt farms.