Shimōsa Plateau
The Bōsō Peninsula is defined by the Pacific Ocean to its east and south, Tokyo Bay to the west, and the Edo and Tone rivers to the north. The Bōsō Hill Range forms the backbone of the south of the peninsula, and much of the area is hilly. Mount Atago in Minamibōsō and Kamogawa is the highest point on the peninsula with an altitude of . From south to north the Bōsō Hill Range gives way to the Shimōsa Plateau, which covers much of the area of northern Chiba Prefecture, and ends in the lower areas around the Tone River.