A strange thing happens when the algae get active in the saltwater lagoons to the south of Aigues-Mortes: the water turns red. To examine this phenomenon close up you can take a ride in one of the miniature trains that skirt the lagoons. If you’re lucky, you’ll also spot flamingos. Website: www.visitesalinsdecamargue.com
Cap d’Agde is home to around a dozen beaches (depending on how you count them), including France’s largest nudist colony. There’s plenty to do too: spas, fitness centres, water sports, tennis, boules, football, bars, restaurants, markets, coastal walks and theme parks are all in good supply. Website: www.en.capdagde.com