下北半島
Ōma occupies the northwestern coastline of Shimokita Peninsula, facing the Tsugaru Strait. is the northernmost point on the island of Honshū. Much of the town is within the limits of the Shimokita Hanto Quasi-National Park. In 2002, the Ministry of the Environment classified some tidal flats of the Ōma shoreline as one of the 500 Important Wetlands in Japan particularly for its biodiversity of marine flora, especially several varieties of kelp.