Onagawa is located on the rugged Sanriku Coast of north-central Miyagi Prefecture, with the Kitakami Mountains to the west and the city of Ishinomaki to the east, south and north. Much of the town is within the borders of the Sanriku Fukkō National Park. Onagawa is a natural deep water port, located at the intersection of two major ocean currents and noted for its commercial fishing industry. Located nearby on the southern side of Onagawa Bay is the Onagawa Nuclear Power Plant.