Blue Bay Marine Park is the finest snorkelling site on the island, a protected lagoon about 8 kilometres south of Mahébourg with exceptional coral diversity and clarity. The water is warm and shallow enough for novice snorkellers, but the coral gardens extend into deeper water that repays more experienced swimmers. The range of fish life — parrotfish, triggerfish, moray eels, and occasional turtles — is outstanding by any standard.
The beach itself is a broad arc of white sand backed by casuarina trees, with calm, protected water. Water sports and snorkelling equipment are available for rent from several operators at the beach. Go on a weekday if you can — weekends bring local families in number and the beach fills up. The park is signposted from the coast road south of Mahébourg.