Bangladeshis call Saint Martin's their only coral island, although no coral reef was ever built here. The island is a drowned tip of the mainland, a sandstone sliver rarely half a kilometre wide lying nine kilometres off the end of the Teknaf peninsula. Its shore is ringed by a boulder field rather than a reef, and twice a day the tide pulls back to expose acres of dark, rounded stone. Corals do live here, and nowhere else in Bangladesh: surveys have recorded 66 species. But they grow only as a thin crust over those boulders, never building a reef of their own, and that crust breaks underfoot. Much of it has already gone. At the southern end, a tail of sand called Chhera Dwip, the torn island, is cut off by every high tide; walk out at low water and you stand on the southernmost land Bangladesh has.
Coconut palms lean over both shores, and the island's Bengali name, Narikel Jinjira, means Coconut Island. At dawn the fishing fleet still hauls its narrow, brightly painted boats straight up the sand. From November into February, olive ridley turtles crawl ashore after dark to lay their eggs on those same beaches. Both had been losing ground: decades of unchecked hotel building, and the crowds drawn by a much-loved 1990 novel, left the wells salty and the coral broken. Bangladesh declared the surrounding waters a marine protected area in 2022, and from the 2024-25 season closed the island to tourists for nine months of every year. You can now come only in a short winter window, on a registered pass, and even the way in has changed: the quick crossing from Teknaf was abandoned after boats were fired on from the Myanmar shore, so the ferry runs from Cox's Bazar instead.