A fragile barrier between the sea, the ponds, and the delta lands, the Camargue beach bordered by dunes forms a 24.8 mi (40 km) long and 328 ft (100 m) wide shoreline. Located at the extreme south of Camargue, from the mouth of Grand Rhône to that of Petit Rhône, this long coastal strip called lido is made up of sand constantly reworked and reshaped by the swell, the wind, the tides, and the sea level rise. It is doubled by a sea dyke intended to protect Camargue from marine invasions.