Numazu is at the northern end of Izu Peninsula and the mouth of the Kamo River. As a narrow area where the Tōkaidō highway connecting Kyoto with Edo must pass between the Pacific Ocean and the foothills of Mount Fuji, Numazu commanded a strategic location and was also a good port for shipping to the Izu Peninsula. The settlement of Numazu prospered in the Edo period as Numazu-juku, and eight generations of the Mizuno clan resided at Numazu castle, with their revenues eventually rising to 50,000 koku.