Aomori (青森市, Aomori-shi) is the capital city of Aomori Prefecture, in Japan. The city faces the Tsugaru Strait via Mutsu Bay to the North and the Hakkōda Mountains to the South. It has the biggest seaport in the prefecture. Before the Seikan Tunnel opened, Port Aomori connected the city via train ferry to Hakodate in Hokkaidō, and therefore the city served as the main entrance to Honshū for passengers and cargo to and from Hokkaidō. Though the town and port were settled in 1626, the city of Aomori was officially founded on April 1, 1898. On April 1, 2005 Aomori increased in size by merging with the neighbouring town of Namioka. Aomori literally means blue (or green) forest. The name is generally considered to refer to a small forest on a hill which existed near the town. This forest was often used by fishermen as a landmark. A different theory suggests the name might have been derived from the Ainu language.