Antsiranana is the capital of Diana Region. It had an estimated population of 115,015 in 2013.
Antsiranana is situated on Antsiranana Bay, one of the largest deep-water harbors in the Indian Ocean, but the remote location, and, until recently, a bad road to the south, rendered it unimportant for freight traffic. Arrachart Airport provides communication primarily with other parts of Madagascar.
The bay and city originally used the name Diego Suarez, named after Diogo Soares, a Portuguese navigator who visited the bay in 1543.
In the 1880s, the bay was coveted by France, which desired it as a coaling station for steamships. After the first Franco-Hova War, Queen Ranavalona III signed a treaty on December 17, 1885 granting France a protectorate over the bay and surrounding territory, as well as the islands of Nosy-Be and Ste. Marie de Madagascar.
The colony's administration was subsumed into that of Madagascar in 1896. The Second Pacific Squadron of Imperial Russia anchored and was resupplied at Diego-Suarez on its way to the Battle of Tsushima in 1905.
In 1942, Diego Suárez was the primary objective of Operation Ironclad, the starting point of the Allied invasion and capture of Madagascar. The Allies were concerned that Japan would pressure Vichy France into granting use of Madagascar, as they had with French Indo-China during the previous year, and determined that the island should not be made a base for the interdiction of Allied shipping. Diego Suarez, with its superlative harbor and a concentration of government officials, was selected as the initial invasion point. The Japanese responded with an attack by midget submarines on the British naval forces in the harbor, damaging the battleship HMS Ramillies and sinking an oil tanker.
France continued to use the city as a military base after Malagasy independence in 1960 and until the socialist revolution of 1973.
Lycée Français Diego Suarez, or Lycée Français Sadi-Carnot, is a French international school in Antsiranana. Historically it was the Collège français Sadi Carnot.
The climactic scenes of the alternative history novel The Madagaskar Plan are set in the city.