Le Grau-du-Roi (French pronunciation: [lə ɡʁo dy ʁwa]; Occitan: Lo Grau dau Rei) is a commune in the Gard department in southern France.

Immediately landwards are the large shallow étangs, saline marshes, which separate it from Aigues Mortes, a neighboring mediaeval walled city that used to be a port.

Le Grau-du-Roi comes from the Occitan word grau (Latin gradus), which refers to the opening of an étang (shallow saline lake), or the watercourse from an etang into the sea.

It is separated from Aigues-Mortes by a series of saline marshes, called étangs in French, and a bend in the river Vidourle.

To the west of the town, the coastal strip is breached where the Vidourle empties into the Mediterranean, and to the east is that of the Petit Rhone.

[6] In 1570, a storm surge from the Rhone entered the etang and breached the coastal strip forming a new grau.

The village, based around fishing cottages, gained administrative buildings and was recognised as a section of Aigues-Mortes in 1867, becoming a separate commune in 1879.

The village of fishers and farmers turned to tourism at the end of the 19th century, with the extension of the Nîmes Aigues-Mortes railway line in 1909:[8] bathers arrived en masse, and on the 26 April 1924 the French President of the Republic decreed that Le Grau-du-Roi was a "station climatique et balnéaire" (beach resort town).

The rail line enabled local producers to market their white grapes and fish nationally.

By 1942, many of the inhabitants had fled: the coast was on the front line and bristled with tank traps and minefields.

Le Grau-du-Roi was liberated in August 1944, and the coast started to rebuild, with a focus on tourism.