大湊警備府
The was the major navy base for the Imperial Japanese Navy in northern Honshu before and during World War II. Located in Mutsu Bay, (at the present-day city of Mutsu, Aomori Prefecture, the Ōminato Guard District was responsible for control of the strategic Tsugaru Strait between Honshu and Hokkaidō and for patrols along the Hokkaidō, Karafuto and Kurile Islands coastlines.