Ré (rā) [key], island (1991 pop. 13,973), 33 sq mi (85 sq km), Charente-Maritime dept., off La Rochelle, W France, in the Bay of Biscay. The island is largely agricultural; it has oyster beds, some fishing, and a salt-extraction industry. There is also tourism. In the late 1970s a 2.1 mi (3.4 km) bridge was completed connecting the island with the mainland. The citadel, built (1681) by Vauban at Saint-Martin-de-Ré, is now a penitentiary. The name was formerly sometimes spelled Rhé.