Blue Bay is where Mauritius's underwater world takes centre stage. The beach itself is fine — a comfortable arc of white sand backed by casuarina trees and the facilities of the adjacent Park Inn hotel — but what makes Blue Bay special, and what has made it the most visited marine site on the island, is what lies beneath the surface. The Blue Bay Marine Park, established as Mauritius's only marine protected area in 2000 and designated a Ramsar wetland site in 2008, encompasses 353 hectares of coral reef, seagrass beds, and open water that together constitute the most biodiverse marine environment in the country.

The coral garden directly off the beach is accessible by snorkel in as little as two metres of water, and the experience is startling in its richness: at least 38 species of hard coral have been recorded in the park, including large table corals, brain corals, and the branching staghorn corals that support the greatest density of fish life. Sergeant majors, parrotfish, wrasse, grouper, triggerfish, and the bright yellow butterflyfish are all visible on a single morning's snorkel without moving more than 50 metres from the beach. Sea turtles are frequent visitors — usually hawksbill, occasionally green — and are so accustomed to the presence of snorkellers that they rarely show any alarm at close approach.

The marine park restricts motorised activities in the core zone, which means the coral remains in excellent condition and the water above it is strikingly quiet. Glass-bottom boat tours operate on a schedule from the beach, which is the way to access the deeper outer reef sections while remaining dry. For certified divers, the outer reef at Blue Bay hosts some of the most dramatic wall and slope diving in Mauritius.

The beach at Blue Bay village is small and fills quickly on weekends with local families from Mahébourg and the surrounding south-east. Arrive before 10am for a shaded spot. The public facilities — toilets, cold showers, and a small café — are at the southern end of the beach near the car park. The snorkel rental operators set up from around 8:30am.