Cayeux-sur-Mer is situated on the Picardy coast.
The ancient name of the city was Caldus, it took the name of Caldis in the 7th century before it was called Caïeu in the 14th century. The city took the name of Cayeux-sur-Mer after a decision of the town council in 1868.
From 1870, Cayeux-sur-Mer made the transformation from a fishing village into a seaside resort becoming the second created in France after Dieppe.