Peros Banhos Atoll

Peros Banhos Atoll sits at the geographic heart of the Chagos Archipelago, its lagoon of some 500 square kilometres making it the second largest in the group, and the atoll itself rises only a few metres above the Indian Ocean on a clear day, the coconut palms on its rim visible as a dark green crown at the horizon.

The lagoon is entered through three channels, each navigable only by vessels drawing less than three to five metres of water, and the coral gatekeepers on either side of these passages are vivid even from a small boat — table corals, brain corals and stands of staghorn forming a shifting mosaic of colour that changes with depth and angle of light.

Historically the atoll was occupied by Franco-Mauritian communities from the late 18th century who developed a salt industry and coconut plantations, exporting salt and coconut products through the Port Louis market, and the remnants of stone salt works and rudimentary jetties are still visible on aerial imagery if not on the ground.

Today the atoll is uninhabited, as are most of the Chagos islands, and there are no facilities for visitors, no regular transport and no infrastructure of any kind, a situation that is unlikely to change given the long-running dispute over the status of the Chagos Archipelago between Britain and Mauritius.

The surrounding waters are among the least disturbed in the Indian Ocean, and the reefs that enclose the lagoon support large colonies of seabirds including sooty terns, red-tailed tropicbirds and brown and black noddies that nest in the casuarina trees and low shrub that fringe the islands.

The legal and diplomatic history of Peros Banhos mirrors that of the entire archipelago: the atoll was administered by France from Mauritius until 1814, transferred to British control after the Napoleonic Wars, and has been under British sovereignty since 1965 when it was excised from Mauritius on the eve of independence.

The reef passages into the lagoon are narrow and serpentine, requiring careful navigation through coral bommies that rise to within a metre of the surface, and the variety of coral species found along these passages — including large gorgonian fans and stands of table coral — is an indication of the overall health of the reef system that fills the lagoon interior.

Peros Banhos has been the subject of scientific interest from marine ecologists studying the Chagos reef system, and surveys conducted in the 1990s and 2000s consistently recorded fish biomass and coral cover significantly higher than comparable Indian Ocean sites, a finding that was instrumental in justifying the 2010 marine protected area designation.

Peros Banhos offers one of the most remote and unspoiled coral reef environments accessible by private vessel in the Indian Ocean, with lagoon passages that reward careful navigation and reefs that show minimal signs of bleaching or Crown-of-Thorns damage.

The atoll's layered colonial history, combining French, Mauritian and British phases across three centuries, is legible in its place names and the remnants of salt works, providing a concrete historical dimension to what is otherwise a purely natural landscape.

The seabird colonies, particularly the sooty tern and red-tailed tropicbird nesting populations, are of regional conservation significance and are monitored under the Chagos Conservation Trust's research programme.