The Tokyo Bay ferry is the secret of this point. It carries motorcycles, and it is the pleasant way to link the two peninsulas, since the alternative is a long drive around the head of the bay or the tunnel and bridge of the Aqua-Line.
Riding the ferry is a break in the middle of the day. The boat is large and slow, with a deck where you can stand and watch the container ships, the fishing boats and the hills of both shores. On a clear day, Mount Fuji is visible to the west, and the sea air is fresh. The road at each end is typical of the Japanese coast, with narrow lanes, tunnels and bends, and a surface that is well kept but with steep gradients. Check the timetable before you go, as sailings can be cancelled in bad weather, and queue early on weekends.
The bay has strategic importance. Commodore Perry's black ships entered it in 1853 to demand that Japan open to trade, and the Uraga channel here was the gateway to Edo. Yokosuka, to the north, is still home to a major naval base, both American and Japanese, and its harbour has historic warships on display. On the Kanaya side, Nokogiri-yama, the Saw Mountain, a ridge of jagged stone, has a quarry, a huge carved Buddha and a lookout called Jigoku Nozoki, or Hell Peek, that overhangs a cliff.
Fuel and food are easy at both ends. Yokosuka has big stations, and the Kanaya port has fish restaurants and a small market, where the local catch, including horse mackerel, is served fried or as sashimi. Convenience stores can supply snacks.
Stand on the deck and watch the shore slide by. It is a calm interlude between two roads.