Egmont Islands

The Egmont Islands form a compact reef platform at the northern edge of the Chagos Archipelago, seven small islands arranged around a shallow lagoon that is enclosed by the reef rim and accessible through a single narrow channel, creating a contained marine environment that is sheltered from the full force of the Indian Ocean swell that can affect the northern reaches of the archipelago.

The islands are low-lying sand cays, typically no more than two metres above sea level at their highest point, and the vegetation is limited to salt-tolerant shrub, a few coconut palms and the scattered casuarina trees that provide nesting sites for the brown noddy and black noddy colonies that are visible from the water as white patches against the green of the island foliage.

What makes the Egmont Islands particularly striking to a diver or snorkeller approaching from the east is the sudden change in water colour from the pale turquoise of the lagoon to the dark indigo of the deep ocean that surrounds the platform, the reef rim dropping away on its ocean side to depths of several hundred metres within a few hundred metres of the island shores.

The dive sites on the outer reef slope are considered some of the most dramatic in the Chagos Archipelago because of this steep bathymetric drop-off, with large gorgonian sea fans, barrel sponges and schools of pennantfish, moon wrasse and doublebar surgeonfish drifting in the current that runs strongly along the reef face.

Historically the Egmont Islands were used as a stopover by sailing vessels navigating between the Maldives and the African coast, and the sandy spit on the western side of the group provided a defensible anchorage in the northeast monsoon season when the winds were contrary for westbound sailing.

The group was named after the Earl of Egmont, who was connected to the early 19th-century British administration of Mauritius from which the Chagos Archipelago was administered, and the name appears on charts and sailing directions from the 1820s onwards as the islands became regular waypoints for vessels transiting the central Indian Ocean.

The Egmont Islands are among the most reliable sites in the Chagos Archipelago for encounters with large pelagic species: the steep drop-off just outside the lagoon channel means that deep-water species are found close to shore, and hammerhead sharks, grey reef sharks and occasional manta rays are reported by the few vessels that have dived the site.

The enclosed lagoon, while shallow, is not sterile: it supports populations of juvenile reef fish, octopuses and occasional eagle rays that use the calmer water for feeding, and the coral gardens along the inner channel walls are among the most colorful parts of the dive, with dense stands of staghorn and table coral in shades of purple, orange and blue.

The Egmont Islands offer a combination of accessible shallow lagoon diving and dramatic deep-water wall diving that is unusual in the Indian Ocean, with the reef drop-off beginning within a few hundred metres of the beach.

The seabird colonies, particularly the brown and black noddies and the lesser noddy, are among the most accessible in the Chagos Archipelago and can be observed at close quarters from a small boat or kayak.

The compact size of the reef platform and the single entrance channel make the Egmont Islands easier to navigate and explore than some of the larger atolls in the group, while retaining the same quality of marine environment.