Sonadia Island

Cox's Bazar · Cox's Bazar District · Bangladesh

Sonadia Island sits just nine kilometres off Cox's Bazar, Bangladesh's most popular beach resort town, yet it remains a world apart — a low-lying tidal island where mangrove forests, sea grass meadows, and rocky formations create an ecosystem of surprising richness in waters more often associated with river sediment than coral. Designated as an Ecologically Critical Area by the Bangladesh government, Sonadia is slowly gaining recognition as an emerging marine destination for snorkellers and adventurous divers. The underwater terrain is dominated by rocky outcrops extending from the island's southern and western shores into the Bay of Bengal. These formations support encrusting corals, sponges, and algae that provide habitat for a surprising diversity of fish. Snapper, grouper, and damselfish dart between the rocks, stingrays rest on sandy patches, and green turtles surface to breathe between foraging runs on the seagrass beds fringing the calmer shores. Sonadia's true ecological significance lies in its role as a nursery and habitat connector. Extensive mangrove forests serve as breeding grounds for mud crabs, shrimp, and juvenile fish that eventually populate offshore reefs. The surrounding waters host a resident population of Irrawaddy dolphins, a vulnerable species found in only a handful of locations across South and Southeast Asia. Horseshoe crabs, living fossils predating the dinosaurs, breed on Sonadia's beaches in one of the last significant populations on the Bangladesh coast. Visibility rarely exceeds ten metres even during the calm dry season from November to March. But what Sonadia lacks in crystal waters it offers in ecological authenticity — this is a working marine ecosystem, not a curated attraction. The island has no dive shops or resort infrastructure, so visitors must arrange boat transport from Cox's Bazar and bring their own snorkelling gear. For those willing to embrace the rough edges, Sonadia provides a rare glimpse into Bay of Bengal biodiversity and a compelling case for its protection.