Aldabra is a large raised atoll located 1150 km southwest of Mahe and 420 km north of Madagascar. The atoll makes up about one third of Seychelles' land mass. Aldabra has been described as "one of the wonders of the world" by Sir David Attenborough as its isolation in a remote area of the Indian Ocean, combined with an inhospitable terrestrial environment, has helped preserve it in a relatively natural state. Increasing levels of stress from human activities are contributing to the decline of the worlds coral reefs, but Aldabra has so far escaped the worst of these stresses and provides an ideal natural laboratory for studying tropical marine ecosystems and related environments (such as seagrass and mangroves). It was declared a World Heritage Site in 1982.

The atoll consits of four main islands; South Island (Grand Terre, 116.1 km²), Malabar or Middle Island (26.8 km²), Polymnieli or Polymnie (4.75 km²) and Picard or West Island (9.4 km²) Additionally, there are some forty smaller islands or rocky islets inside the lagoon.

Aldabra is formed from late Quaternary raised reef limestones, averaging 2km in width and up to 8m above sea level, and rimming a shallow central lagoon. The atoll is home to the world's largest population of giant tortoises, numbering some 152,000 individuals (that's fiev times as many as the Galapagos!). The islands are also well known for their green turtles, hawksbill turtles, and birds, including the last remaining flightless bird of the Indian Ocean, the white-throated rail. In addition there is the Aldabra drongo and unique varieties of sunbird, foddy, white-eyed bulbul, nightjar, coucal, pigeon and turtle dove. Huge colonies of spectacular lesser and great frigate-birds breed alongside red-footed boobies in the mangroves which border the northern rim of thee huge lagoon.

The shallow waters are patrolled by dimorphic egrets, found only on Madagascar and the Aldabra group of islands. Along the shoreline, the Aldabra sacred Ibis together with a whole host of black-napped and crested terns including caspians may be seen. Other birds include the greater flamingo and the malagasy kestrel, which are probably recent colonists. The steep walls around the raised limestone islands of Aldabra atoll have rarely been dived. Fish life is prolific while over 2000 green turtles breed on the beaches each year. Dolphins and occasionally whales can be seen offshore. Until recently, it has only been possible to visit Aldabra by cruise ship or chartered yacht from Mahé. However, an airstrip has been constructed on Assumption Island, which lies to the south of Aldabra. Accommodation will soon be available for limited numbers on both Assumption and Aldabra. Guides, trained by the Seychelles Islands Foundation, which administers the atoll, will soon be able to reveal the treasures of this unique world to those who seek one of the last unexplored corners of the world.