Giant turtles, mangroves, coral reefs... 1 OCEAN sets out to discover one of the world's best-preserved ecosystems: Aldabra, the atoll at the end of the world. In search of the original, Alexis Rosenfeld and his team offer an enchanting account of the atoll's countless biotopes, which follow one another and intermingle in total interdependence.

The treasures of Aldabra have long been the stuff of exploration fantasies. You have to travel 1200 km from Mahé, the main island of the Seychelles, to reach this immense atoll in the heart of the Indian Ocean. Difficult access and the absence of fresh water make it an inhospitable land for man, but a protective environment for its 400 endemic species.

The atoll is one of the very first marine sites to be classified as a World Heritage Site by UNESCO (1982), and its isolation allows us to observe life as it existed millennia ago.

The world's largest raised atoll conceals a lagoon ring that empties and fills twice a day, to the rhythm of the tides. The spectacle is extraordinary: when the water recedes, mushroom-like islets appear, eroded by the waves. The fresh trade wind rushes through the mangrove leaves, their rustling mingling with the songs of the Souimangas. Some 150,000 giant tortoises take part in the picture.

Indeed, Aldabra is home to the world's largest population of giant tortoises. They are the last survivors of a life form once widespread on other Indian Ocean islands, of which Aldabra is now the only remaining habitat. Green turtles, considered endangered by the IUCN, also find refuge here, and have seen their population increase by 500-800% in recent decades.

essential to the balance of life on the atoll, mangroves cover 11% of the atoll. Proportionally, this is one of the highest levels of mangrove cover in the world. A veritable link between land and ocean, the mangrove is both a nursery for numerous species and a protective barrier against erosion.