The is a peninsula that encompasses the entirety of Chiba Prefecture on Honshu, the largest island of Japan. It is part of the Greater Tokyo Area. It forms the eastern edge of Tokyo Bay, separating it from the Pacific Ocean. The peninsula covers approximately .
Description
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. 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.