Saint Martin's Island tide times

Saint Martin's Island — Narikel Jinjira (Coconut Island) in Bengali — is the only coral island in Bangladesh, sitting 9 kilometres south of Teknaf at the tip of the Cox's Bazar peninsula and separated from the Bangladesh coast by the Naf River estuary. The island is approximately 8 square kilometres and rises no more than 3 metres above sea level. It has a permanent resident population of approximately 8,000 people, living primarily from fishing and, increasingly, from the tourism that peaks in the dry season (November to March) when the ferry from Teknaf operates.

The coral reef surrounding Saint Martin's is the northernmost in the Bay of Bengal. Coral growth here is at the thermal limit — water temperatures drop to 22 to 23 degrees Celsius in winter months (December to February), close to the threshold below which coral growth rates slow significantly and bleaching stress from cold becomes a factor. The coral communities are less diverse than tropical reefs at lower latitudes, but they are more biodiverse than surrounding non-coral coastal environments and are nationally significant as Bangladesh's only reef ecosystem. The reef supports over 150 species of coral, 240 species of fish, and 150 species of mollusc documented in surveys.

The tidal regime at Saint Martin's is semidiurnal with a spring range of approximately 1.5 to 2.0 metres — noticeably less than the 3.5 to 4.5 metre range at Cox's Bazar 100 kilometres north. The reduction in range reflects the island's open ocean exposure relative to the semi-enclosed northern Bay of Bengal bay geometry. At low water springs, the inter-tidal reef flat around the island is exposed for 50 to 100 metres, revealing the upper coral community. The reef flat is accessible on foot in calm conditions; coral walking causes irreversible damage to the living colonies and should be avoided.

The ferry from Teknaf operates from November to March when Bay of Bengal sea conditions permit — typically 8 to 9 months of calm followed by the monsoon period when the passage is unsafe for the vessels used. The ferry takes approximately 2.5 hours from Teknaf. Day visitors return on the same day's ferry; overnight visitors stay in the island's guesthouse accommodation. The island has a small permanent market, basic medical facility, and a police post. Fresh water is limited in the dry season — the island's aquifer is recharged by monsoon rain, and the supply is managed carefully through the dry season.

Sea turtles nest on the beaches of Saint Martin's Island. Olive ridley turtle (Lepidochelys olivacea) and green turtle (Chelonia mydas) nesting has been documented; the beach on the northern and eastern faces is used for nesting in the winter months (November to February). The Department of Fisheries has run a sea turtle monitoring programme on the island. Visitors should not approach nesting turtles or hatchlings and should not use torchlight on nesting beaches after dark.

Snorkelling off the island's southern and eastern reef face is the primary water activity. The reef is in 2 to 8 metres on the shallow sections and is accessible without a boat from the beach at low to mid-tide. Visibility is typically 5 to 10 metres on settled days. Several local snorkel operators offer guided sessions and equipment rental on the island.

Predictions on this page come from Open-Meteo Marine, a gridded global ocean model. Accuracy is typically within plus or minus 45 minutes on timing and 0.2 to 0.3 metres on height — model-derived, not from a local gauge. The local tide authority is the Bangladesh Meteorological Department (BMD).