The Trans-Tokyo Bay Highway, also known as the Tokyo Bay Aqualine, is a 15.1 km marine crossing through the middle of Tokyo Bay connecting Kawasaki City in Kanagawa Prefecture with Kisarazu City in Chiba Prefecture on the Boso Peninsular. With the journey from Kawasaki to Kisarazu now taking just 15 minutes, the highway plays a vital economic role in integrating these two areas of prime industrial importance.
bridge and 9.6 km tunnel underneath the bay—the fourth-longest underwater tunnel in the world