What it is
A ring of four large coral islands enclosing a vast tidal lagoon, roughly 1,100 km southwest of Mahé and much closer to the African mainland than to the rest of Seychelles. It holds the largest giant tortoise population on earth, over 100,000 animals, along with the last flightless bird in the Indian Ocean. It is UNESCO-listed and managed as a strict research reserve by the Seychelles Islands Foundation.
Why go
It is the least disturbed island ecosystem left in the ocean. That is also precisely why access is controlled.
When to go
Be plain about this: there are no scheduled flights, no hotel and no ferry. The only way there is a permitted expedition voyage, usually a live-aboard or a small expedition ship, running a handful of times a year, taking several days each way at sea, requiring a permit from the Foundation, and costing many times a normal Seychelles holiday. Do not build a trip around it. If you want giant tortoises, Curieuse off Praslin has hundreds of them and is a 15-minute boat ride.
Most people stay Expedition only.