St. Martin's Island is a small island in the northeastern part of the Bay of Bengal, about 9 km south of the tip of the Cox's Bazar-Teknaf peninsula, and forming the southernmost part of Bangladesh. It is about 8 km west of the northwest coast of Myanmar, at the mouth of the Naf River.

The local name of the island is "Narical Gingira", also spelled "Narikel Jinjira/Jinjera", translated from Bangla, meaning 'Coconut Island'.

It is the only coral island in Bangladesh. Most of the island's 5500 inhabitants live primarily from fishing. Besides, the other staple crops are rice and coconut. Being very common in the island, Algae is collected, then dried and finally exported to Myanmar.

Between October and April, the fishermen from neighbouring areas bring their caught fishes to the island's temporary wholesale market. As the centre and the south are mainly farmland and makeshift huts, most of the strenuous things are around the far north of the island.

Motel Nijhum is one of the best hotels in St. Martin’s Island. Besides,Abokash,Nil Diganta,Blue Marine, Prashad Paradise and Sraboni Bilash are also well known hotels. All these hotels are situated near the seashore.