Antsiranana Bay (also known as Diego-Suarez Bay) is a natural bay that stretches close to 20 km north to south along the northeast coast of Madagascar. The waters average a depth of more than 20 m, and the main channel can be as deep as 50 m. The bay, protected by a narrow inlet that provides shelter from strong Indian Ocean winds, is believed to be the result of a submerging coastline or a drowned river valley that formed many peninsulas around the bay. The bay's principal city, Antsiranana, is located on a headland.

History

The bay was first recorded by European explorers in 1500; sailors in the service of Portugal named the bay for the leader of their expedition, Diogo Soares. The bay was later used for shelter by a number of pirates and privateers during the Golden Age of Piracy, and it has been speculated as a possible location of the legendary pirate colony Libertalia.