British Indian Ocean Territory

The Great Chagos Bank is the largest atoll structure on Earth, a vast underwater mountain range crowned by a constellation of coral islands. Spanning over 12,000 square kilometers, it is a colossal biological engine that drives ocean currents and marine populations across the central Indian Ocean. The sheer scale of this living coral structure is a magnet for elite scientific researchers and deep-water divers. Navigating its outer rim offers the rare majesty of ecological true wilderness, where human footprint vanishes entirely beneath the waves.

Île du Coin is a medium-sized coral island in the Peros Banhos atoll, notable for its distinctly jagged and tombolo-like geography where sandbars connect smaller islets. The island is a dense thicket of mature coconut palms and scrubby vegetation, creating a classic, almost stereotypical image of a deserted tropical island. The surrounding waters are a striking gradient of turquoise and deep sapphire, offering spectacular visibility for snorkeling over the shallow reef flats. While it lacks the historical ruins of Île Boddam, its raw, unadulterated natural beauty is captivating. It is a place of absolute silence, broken only by the rustle of palm fronds and the gentle lap of waves. For the rare few who pass through, it is a fleeting, postcard-perfect moment of tropical isolation.

Blenheim Reef is a geographically fascinating and virtually inaccessible atoll located northeast of Diego Garcia. Submerged for much of its circumference with only a few tiny islets emerging from the crystalline waters, it is a sanctuary for pelagic marine life and migratory birds. The lagoon harbors deep channels and shifting sandbanks, presenting a dramatic canvas of turquoise against the deep ocean blue. It represents the absolute pinnacle of isolation for the few arctic ocean voyagers who dare the passage into the Chagos waters.

Danger Island, aptly named for its hazardous reefs and relative inaccessibility in the western Chagos, epitomises the raw, unforgiving nature of remote atolls. Surrounded by extensive coral reefs and deep oceanic depths, it has deterred casual visitors for generations, preserving its near-virgin state. Few human traces mar this site; instead the landscape is dominated by driftwood, seabird colonies, and resilient coastal scrub. The ocean surrounding the island can be treacherous, but biologically it remains extraordinarily rich, holding strong populations of reef fish, turtles, and pelagic migrants. This island is emblematic of far-flung wilderness in the central Indian Ocean; a place of risk and reward where the boldest eco-expedition travellers can witness the last wild atolls of the region.

Île Boddam is the largest and most significant island in the Peros Banhos atoll, serving as a hauntingly beautiful relic of the Chagos Archipelago’s past. Characterized by towering rustling casuarina trees and the crumbling, sun-bleached remains of a former copra plantation and village, the island offers a profound sense of isolation. Overgrown paths wind past fallen coral-rag walls and sunken foundations, slowly being consumed by the jungle. Today, it is a sanctuary for vast nesting colonies of seabirds and massive coconut crabs, untouched by modern tourism. While access is virtually impossible for casual visitors due to strict military and environmental protections, for those with special permission, it represents one of the last truly deserted tropical paradises on Earth.

Île de la Passe is a small, low-lying coral island situated near the entrance to the Peros Banhos lagoon. Its name, translating to ‘Island of the Pass’, hints at its historical role as a navigational marker for ships seeking safe passage through the treacherous outer reef. Today, it is a quiet, windswept sliver of sand and scrub, largely devoid of the dense jungle found on the larger inner islands. The landscape is stark and elemental, dominated by low-lying bushes and the bleached skeletons of fallen trees. While it lacks the lush, romantic appeal of its neighbors, it offers a raw, windswept beauty and a profound sense of being at the very edge of the world. It is a place best appreciated from the deck of a passing vessel, a fleeting glimpse of the ocean’s vastness.

Perched on the eastern edge of the Peros Banhos atoll, Île Fouquet is a narrow, densely wooded ribbon of sand and coral. Covered in thick, almost impenetrable tropical vegetation, it is a world away from the manicured beaches of modern resort islands. The shoreline is composed of crunching white coral sand, littered with gnarled driftwood and the occasional abandoned fishing float from decades past. While it lacks the deep-harbor pull of its larger neighbors, Île Fouquet boasts a remarkably wild aesthetic. It serves as an undisturbed rookery for terns and frigatebirds, whose cries echo across the quiet shallows. It is a visually striking place, yet its sheer isolation and lack of infrastructure relegate it to the status of a fleeting, majestic visual for those navigating the outer reef, rather than a destination.

Nelsons Island, a solitary, elongated islet on the northern rim of the Great Chagos Bank, is one of the most secluded landmasses in the territory. Scattered with dense coconut palms and low forest, its beaches are patrolled by fruit bats and flocks of frigatebirds and terns. Historical traces include intermittent copra collection and, more recently, surveys by marine scientists measuring reef resilience. The island’s isolation provides refuge for green turtles and a thriving marine ecosystem, with strong currents flowing past its edges boosting nutrient delivery and attracting larger pelagics. Encountering Nelsons Island is reserved for the most determined explorers, often sailing yachts on Indian Ocean crossings. Those who do set foot here feel the profound stillness of one of the last uninhabited coral islands in the Indian Ocean.

Sea Cow Island (Île Vache Marine), named after the once-widespread dugong, is a small, low-profile coral islet in the southern reaches of the Chagos Archipelago. Despite its modest size and elevation, it plays an outsised role in regional ecology, serving as a nesting site for native seabirds and sea turtles. The surrounding waters provide a gentle snorkelling experience among branching corals and lagoon fish. The remnant dugong legacy lends a sense of ecological melancholy and wonder, evoking a time when marine mammals roamed these shallows more freely. Few visitors reach Sea Cow Island; those who do encounter a serene, sun-bleached landscape where human history feels fleeting against the backdrop of ocean currents and birdcalls. It is an ideal destination for marine biologists, conservation-minded sailors, and photographers seeking remote, evocative imagery.

Lying within the stunning Peros Banhos atoll, Île Anglaise is a large, virtually uninhabited island world-renowned among a very niche community of extreme sailors and researchers. Its defining feature is a massive, deep-water lagoon that acts as a natural harbor. The island is a pristine wilderness where coconut palms cast long shadows over untouched coral sands, and the surrounding reef walls teem with vibrant marine life, including technicolor coral gardens and curious reef sharks. Stripped of permanent residents and infrastructure, it remains a blank canvas of tropical perfection. Because of its extreme remoteness and the total ban on recreational tourism in BIOT, visiting is an unattainable dream for nearly all travelers, yet it stands as a peerless natural gallery of the Indian Ocean.