Along the coast of the Camargue region, the fortified city of Aigues-Mortes sits enthroned surrounded by salt marshes with signature pink color generated by the presence of the microscopic algae Dunaliella salina. The seawater used to produce the local fleur de sel is pumped directly from the Mediterranean then crosses five different basins that gradually increase its salinity rate. Once the water has been drained, only a 2 to 3 inches (5 to 8 cm) layer of salt remains, called a salt cake, which covers the bottom of the basins. This layer of white gold for which the region is famous was once harvested by salt workers, but its harvesting is now entirely mechanized.