The Pertuis d'Antioche is a strait on the Atlantic coast of Western France between two islands; Île de Ré to the north, and Oléron to the south. To the east lies the continental coast between the cities of La Rochelle and the naval arsenal of Rochefort; to the west the open ocean. The channel is above a league in breadth, and at the northern point of Oleron lies a ledge of rocks called the Antioches, with which the channel shares its name. The ledge extends a quarter league wide of the coast of Oleron, obliging traffic to follow the middle of the channel. The position of the ledge, and the entrance to the channel, was in past times marked with a lighthouse. The link with Antioch, a city in Syria, is unclear.