Aldabra, by virtue of its geographic isolation and through the efforts of dedicated conservationists, has withstood the ravages caused by centuries of passing mariners, escaped the environmental destruction wrought by large-scale human habitation, and today shelters flora and fauna in astonishing numbers and variety.
The largest raised coral atoll on earth, Aldabra has a perimeter of roughly 70 miles. First-time travelers cannot help but be stunned by the sheer scale of Aldabra; inside the lagoon, the opposite end of the atoll dips below the horizon, and each side is too distant to make out. Four large channels cut through Aldabra, allowing ingress and separating it into four main islands—Picard, Polymnie, Malabar, and Grand Terre—along with a number of smaller islands and champignons, fantastically shaped limestone formations.
The atoll is a primordial place, where technology and human will must bow to the rhythms of the natural world. Sunrise, sunset, and the tides hold sway, governing all activities, a fact immediately impressed upon me when I first traveled to Aldabra in 1995. With the challenging, utterly tide-dependent landings and almost complete absence of humankind, the experience had the feel of pure expedition. As the tide rises, millions of gallons of water rush into the lagoon. The force of this influx can make navigating a Zodiac through the channels somewhat tricky, but once we're inside, the shallow draft of our inflatable boats allows freedom to explore before escaping with the falling tide.
Drift snorkels from Zodiacs take advantage of these currents and provide an underwater experience unlike any other. Positioning ourselves at the entrance of a channel, we enter the water and surrender to the tide's inertia. The incoming surge of clear ocean water brings with it a multitude of marine creatures, entering the lagoon to feed. Black-tipped reef sharks, rays, groupers, parrotfish, turtles, and more race beneath us. Riding the tide in this fashion, we feel almost as if we are flying.
While humans found the landscape of Aldabra inhospitable, many different types of wildlife thrive there, and our explorations above the waves will be as remarkable as our underwater adventures. Aldabra's size means that its islands contain vegetation not often found on atolls, including 273 species of flowering plants and ferns, of which, 22 percent are endemic. This incredibly high rate of endemism, much like that of Madagascar, results from Aldabra's isolation. The main islands have extensive mangrove habitats that support fish nurseries and birdlife, including lesser and greater frigatebirds. The champignon islets provide nesting sites for thousands of these birds, as well as their neighbors the red-footed boobies, who are often the victims of piratical aerial attacks by the frigatebirds. On our most recent visits we also spotted Souimanga sunbirds, sacred ibises, Madagascar coucals, and Aldabra flightless rails—the only remaining flightless bird found on any Indian Ocean island. Hungry sailors and introduced predators hunted all the other flightless species, such as the hapless dodo, to extinction.
Aldabra's most famous inhabitant is the giant tortoise. These armored reptiles are usually associated with the Galapagos Islands; yet, the number of tortoises on Aldabra is far greater than that in the Galapagos—between 100,000 and 120,000 on Aldabra compared to approximately 10,000 in the Galapagos. The sun's movement dictates the tortoises' schedule. As it rises, they awaken to feed; they then seek shade to escape the midday heat; when the sun sinks below the horizon, the tortoises fall asleep in their tracks.
Aldabra lay far off the usual shipping routes, and sailors landed there less frequently than they did on other atolls and islands in the Seychelles. The only people here now work at a small research station. Conservation and Aldabra have had a long, fruitful relationship. Charles Darwin championed preservation efforts, and attempts by Britain to install a military base were defeated in the 1960s. UNESCO, recognizing Aldabra's importance, designated it a World Heritage Site. A plaque commemorates this; its inscription reads: "Aldabra, wonder of nature given to humanity by the people of the Republic of Seychelles."
No other words are needed. The frigatebirds wheeling in the sky, the tortoises progressing across the landscape, and the spotted eagle rays skirting the reef are all far more eloquent.