Arcachon Bay and Nearby Lakes, France44.6N 1.1W
Arcachon Bay (top) in French the Bassin d’Arcachon, is a bay of the Atlantic Ocean on the southwest sea shore of France, situated as a landmark between the Côte d’Argent and the Côte des Landes, in the region of Aquitaine. The bay covers an area of 150 km² at high tide and 40 km² at low tide. Some of its geological features are natural preservation areas.
The general shape of the Bassin d’Arcachon is that of an equilateral triangle pointing north, the southwest corner of which is opened and the access from the sea, between Cape Ferret and the town of Arcachon (more specifically, its suburb Pyla-sur-Mer), through a 3 km narrow channel (Les Passes). On the north shore is the town of Arès, then Andernos-les-Bains on the northeast. Just south of the entrance is The Great Dune of Pyla.
It is perhaps due to the Eyre River that runs water from the Landes forest and has its mouth (Delta de l’Eyre) in its southeast corner, that the Bassin still has a link to the sea, which would otherwise be obstructed by the sandbanks brought about by the tides.
A similar process of changing from a bay to a lake occurred long ago to other nearby bodies of water along the coastline, which nowadays are filled with fresh water. Two such bays-turned-lakes are the Étang de Cazaux et de Sanguinet (south of the bay) and the Lac de Biscarrosse et de Parentis (south of the former).
Étang de Cazaux et de Sanguinet is a lake in Gironde, Landes, France. It is situated at an elevation of 12 m and has a surface area of 55 km². Lac de Biscarrosse et de Parentis is a lake in Landes, France. At an elevation of 19 m, its surface area is 35.4 km².