Aldabra Island

Aldabra is a raised coral atoll in the southwestern Indian Ocean, part of the Seychelles and about 630 kilometres from Africa. It is 34 kilometres long and 13 kilometres wide and encloses a shallow lagoon of about 196 square kilometres. Fringing reef surrounds the atoll, while much of the lagoon drains at low tide. The islands have no surface freshwater, and their rugged limestone made permanent settlement difficult.

Arab and Persian seafarers knew the place before Portuguese navigators visited in 1511. The name Aldabra, originally Al-Hadra or Al-Khadra, referred to its harsh, sun-baked environment and appeared on sixteenth-century Portuguese maps. Europeans had little reason to settle an atoll without fresh water; in the mid-eighteenth century, when Aldabra became a dependency of French Réunion, expeditions instead sought giant tortoises for food. The atoll passed to Britain in 1810 with Mauritius and nearby islands, and became part of Seychelles at independence.

The shallow lagoon, reef edge and open ocean are closely linked. Monsoon winds and currents carry nutrients and larvae, while low tides expose large areas of the lagoon floor. Giant tortoises, marine turtles and large seabird colonies make the atoll a major refuge for western Indian Ocean life. Its isolation and limited freshwater explain why human use remained extractive and intermittent until later conservation.