MMnemba Island is a single small island located about 2 km off the northeast coast of Unguja, the largest island of the Zanzibar Archipelago, Tanzania, opposite Matemwe Beach. It is roughly triangular in shape, about 500 m in diameter and about 1.5 km in circumference. It is surrounded by an oval reef seven by four kilometres in extent. These reefs have been declared a Marine Conservation area. Mnemba Island and its reef are sometimes called Mnemba Atoll which is incorrect because an atoll is an island that encircles a lagoon, which is not the case for Mnemba Island