Coral reef thumb|302x302px|L'Ermitage Lagoon Because the island is relatively young (3 million years old),Emmanuel Tessier, Saint Denis, Thèse de doctorat sous la direction de Pascale Chabanet et Catherine Aliaume, 2005, 254 p the coral formations (8,000 years old) are not well developed and occupy a small area compared to older islands, mostly in the form of fringing reefs.
Coral reef thumb|302x302px|L'Ermitage Lagoon Because the island is relatively young (3 million years old),Emmanuel Tessier, Saint Denis, Thèse de doctorat sous la direction de Pascale Chabanet et Catherine Aliaume, 2005, 254 p the coral formations (8,000 years old) are not well developed and occupy a small area compared to older islands, mostly in the form of fringing reefs.