The staghorn coral colonies off Blue Bay grow at roughly ten centimetres a year, which means some of the branching thickets a snorkeller floats over today began forming before Mauritius gained independence in 1968.
That slow arithmetic explains why the lagoon was fenced with legal protection rather than left to the boats. Declared a Marine Protected Area in 1997 and gazetted as a full Marine Park in 2000, Blue Bay covers 353 hectares of shallow water on the island's south-eastern shoulder, near Mahébourg.
The geography is unusual. A near-continuous barrier reef closes the bay against the Indian Ocean swell, leaving a lagoon that rarely exceeds five and a half metres in depth and stays warm year-round. Freshwater runoff is minimal here, and the sandy substrate holds little sediment. The result is the clarity that made a blue bay marine park snorkeling tour a fixture of the Mauritian itinerary long before mass tourism arrived. Surveys have recorded more than fifty coral species inside the park boundary, among them a brain coral colony estimated at over a thousand years old and standing some four metres tall — one of the largest documented in the western Indian Ocean.
The fish assemblage is equally dense. Parrotfish, sergeant majors, moorish idols, damselfish and the occasional green turtle move through the coral heads, feeding on algae that would otherwise smother the reef. Fisheries officers patrol the zone; anchoring, spearfishing and coral collection are prohibited, and boats operating inside the park carry permits. Motorised watersports are excluded from the core conservation area, which is why glass-bottom vessels and gentle drift snorkelling dominate the local fleet rather than jet skis.
What gives the site its contemporary weight is fragility. The 2016 and 2019 bleaching events left visible scarring on the outer reef flat, and the 2020 Wakashio grounding at nearby Pointe d'Esny concentrated national attention on this stretch of coast. Restoration nurseries, coral transplant plots and monitoring transects now sit alongside the tourist moorings. Blue Bay has become a working laboratory as much as a lagoon.
Entry to the park itself costs 0 MUR — the water is free to all, and fees attach only to private boat tours or equipment hire. Local operators run everything from glass-bottom boat crossings over the coral gardens to five-island speedboat circuits taking in Île aux Aigrettes, Île des Deux Cocos and the wider east-coast archipelago. For visitors weighing a blue bay marine park snorkeling tour against a wider lagoon circuit, the distinction is scope rather than quality: the coral is the same, the horizon is not.
7 hr
