Oléron (ôlārôNˈ) [key], island (1990 pop. 18,453), 68 sq mi (176 sq km), Charente-Maritime dept., W France, in the Bay of Biscay. It is an oystering, farming, and ranching area and a summer vacation spot. The Law of Oléron (see maritime law), promulgated by Louis IX, was named after the island. Oléron was a stronghold of Protestantism in the 16th cent. A bridge (1966) links it with the mainland.