The population of the town is approximately 10,000. The municipality of Hamina includes the town and is populated by totally 22,000 inhabitants on the area of 630,65 km².
The port is specialised in forest products and transit cargo to Russia.
The town of Hamina is surrounded by a star-shaped fortress. Construction of the fortress began in 1723 after the Great Northern War, when the territories east of Hamina had been ceded to Russia, and completed after the Finnish War in the beginning of the 19th century, when Sweden had been split and the eastern half had been made a Grand Duchy in personal union with Russia.
The corners of the fortress form six bastions, named after towns in Finland. The Central Bastion was added at the end of the 18th century, and is currently used for cultural events.
The Treaty of Fredrikshamn (1809), by which Sweden ceeded Åland, parts of the provinces Lapponia and Westrobothnia (east of the Tornio river) and all provinces east thereof, was signed in Hamina.