Cap Ferret lies at the southern end of a long sand spit in western France. It separates the Arcachon Lagoon from the Atlantic Ocean and forms part of the spectacular Aquitaine coast, which at 143 miles (230 km) is the longest sandy coast in Europe. This region is characterized by a series of straight, sandy beaches backed by longitudinal sand dunes, which are the highest dune formations in Europe. They include the highest individual European sand dune, the Dune du Pilat, which rises to about 380 ft (115 m) above sea level.
Behind the main dune area is a forest, originally planted in the 18th century to try to prevent the dunes from shifting. Unfortunately, this coast is undergoing serious erosion, of more than 33 ft (10 m) a year in some places, mainly because excessive urban development has degraded the vegetation cover.