Accessed by a 90-minute boat ride from neighbouring Astove, Cosmoledo Atoll is one of the largest uninhabited atolls in the Seychelles and is about as close as you can get to diving the final frontier.
Comprised of 19 wild islands separated by shallow channels, very few have explored beneath the waves of Cosmoledo, and while some sites have been mapped out divers will have the rare opportunity to uncover much of the atoll's vast, colourful reefs and sites for the first time.
Due to the atoll's immense size, diving is done from a day boat or liveaboard. The north-west of the atoll boasts the highest percentage of hard coral cover found in the Seychelles, with potato groupers, turtles, trevally and dogtooth tuna ruling the roost (as well as the occasional hammerhead shark). Over near Gaulette island large coral bommies rise from the substrate, topped with a confetti of colourful fusiliers, turtles, trevally and silvertip sharks. The shallow channels separating the islands are a haven for snorkellers, with eagle rays and reef sharks regularly spotted.
As well as offering exceptional diving, Cosmoledo Atoll is also one of the world's premier destinations for saltwater fly fishing, with vast sand flats, lagoons and offshore sites. Led by an expert guide, visitors can catch (using barbless hooks) bluefin trevallies, permit, milkfish and giant trevallies (which you may remember from Blue Planet II) before releasing them back into the wild.
Conservation runs through the veins of Cosmoledo as reflected by a wealth of eco-activities worthy of Attenborough, from turtle tagging and monitoring to educational island walks led by the Island Conservation Society and ocean clean-ups.