Plâge des Raisins Clairs
It's close to the town of Saint-Francois, next to a cheerful graveyard. Keeping in mind that I was there with my husband before tourist season began, it might not be the same come Christmas, but in November there were only a handful of people on the beach every day. The sand is soft and white, sloping gently into the sea. This swimmer is standing about 3 meters from the shore. It's so clear and calm because the cove is protected by a coral reef.
What's more, there are plenty of sea-grape trees scattered for shade, a restaurant with a terrace, and a snack stand where the owner will sqeeze fresh passion or star fruit juice for you. Somehow, the passing showers that plagued us on other beaches never followed us to this one.
This is also one of the beaches where topless sunbathing seems to be really tolerated - theoretically, it's permissable everywhere on the island, being technically France and all, but you might be harassed on some of the other beaches (in Sainte-Anne, for example).
P.S. This is a sea grape tree, from which the beach takes it name.