Grau-du-Roi was originally a small fishing port lying between the lagoon and the sea." Grau" means passage,thus Grau-du-Roi signifies "king's passage" a name adopted by the port. In 1580, a flooding of the Rhone river provoked an opening in the narrowest part of the off-shore bar, in fact the part which is presently the city. The harnessing of this opening was necessary in order to restore the port and allowing boats to approach Aigues-Mortes , the mother city. Grau-du-Roi in the beginning was but a few fishermen's huts which lined the coast , it was only toward the middle of the 19th century that this village developed enough to seperate fom Aigues-Mortes. Today, Grau-du Roi remains traditional, one can still watch the return of trawlers from sea.