Aldabra Atoll, Seychelles

Aldabra Atoll stands as one of the least disturbed coral ecosystems on the planet, with 100,000 giant tortoises roaming its islands and 90% of its reefs remaining in excellent condition since baseline surveys in 1979. This UNESCO World Heritage site in the Seychelles has recorded coral cover averaging 45% on its outer slopes, which is 25% higher than the global average for Indian Ocean atolls. Its remoteness—a 1,000-kilometer journey from the nearest major island—limits tourism to fewer than 1,200 visitors per year, preserving a marine biomass that significantly outperforms Palancar Reef (#8) in large predatory fish sightings.