Access to Aldabra Atoll, over 1 000km from Mahé, and with four main islands stretching around the world's largest lagoon, is strictly regulated. Designated a UNESCO World Heritage Site, it is mainly known for the giant land turtles that live in the wild here (between 70 000 and 180 000), not to mention the sea turtles and teeming seabird population, chiefly composed of terns and frigate birds.