One of your first stops should be Office de Tourisme de la Grande Motte. Here, you'll be able to find your bearings and get some great ideas before you set out exploring.
Located in La Grande-Motte, this tourist information center is well worth including on your itinerary. But you'll find loads more to check out in this area. Constance Tower, Port-Camargue, and La Grande Motte Beach aren't too far from Office de Tourisme de la Grande Motte.