Aldabra Atoll

Aldabra is the Seychelles' great wilderness: a vast raised coral atoll far out in the Indian Ocean, so remote and so difficult to land on that it survived almost untouched by humans. It shelters the world's largest population of giant tortoises - over a hundred thousand of them, far more than the Galapagos - along with the last flightless bird of the Indian Ocean, the Aldabra rail, plus nesting green turtles, frigatebird colonies and a lagoon so big that at low tide the water pours out through the channels like a river. UNESCO listed it in 1982, and access is tightly controlled by the foundation that manages it.

What you actually see

• The giant tortoises - free-ranging in numbers found nowhere else.
• The Aldabra rail - the Indian Ocean's last flightless bird.
• The tidal lagoon channels - enormous water movement twice a day.
• Seabird colonies - frigatebirds and boobies nesting in thousands.

When to go

Expedition vessels favour the calmer inter-monsoon windows, roughly March to May and September to November. Green turtle nesting and seabird breeding follow their own calendars, and operators plan around them. There is no casual season - trips run rarely and are scheduled long in advance.

Honest expectations

This is not a destination you can simply book: visits require permits through the Seychelles Islands Foundation, come on a handful of expedition cruises or research charters a year, cost a great deal, and involve days at sea to reach. Landings depend entirely on weather and tide. Anyone hoping for a Seychelles beach holiday should look at Mahe, Praslin or La Digue instead - Aldabra is for people who want the wildest place in the region and accept the price and the uncertainty.

Nearby

The other outer islands and the Amirantes group lie on the same distant expedition routes.