Arcachon Bay is located in the heart of the Landes de Gascogne (Gascony). It is triangular in form, and its borders are set by 80 km of flat coastline or wooded sand dunes. It opens mostly onto the Gulf of Gascony, the tide brings considerable amounts of water in and out twice a day. The ‘Bassin’ is partially cut off from the ocean by a line of sand dunes that is notably comprised of Cap Ferret, the Dune du Pilat and le Banc d’Arguin. There is only one way out to the Atlantic Ocean: the channels that are approximately 3 km wide and allow the water to circulate between the bay and the ocean. At the centre of the bay lies l’ile aux Oiseaux, or ‘the Isle of Birds’, plus its famous huts on stilts in the water.