Kesennuma is a city located in the extreme northeast of Miyagi Prefecture, Japan, founded on June 1, 1953. It wraps around the western part of Kesennuma Bay, and also includes the island of Oshima. Its coastline forms the southern boundary of the Rias Coastline National Park, which stretches north all the way to Aomori Prefecture.
The city borders Hirota Bay, Kesennuma Bay, and the Pacific Ocean to the east and Minamisanriku, Miyagi to the south. Iwate Prefecture makes up the remainder of its borders, with Murone Village to the west, and Rikuzen-Takata City to the north. The highest point in Kesennuma is 711.9 m high, on the border with Motoyoshi, while the lowest point is at sea level.
Large sections of the city were destroyed by the 2011 Tohoku earthquake and tsunami and major fires on March 11, 2011.