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The Tokyo Bay Aqua-Line Expressway makes Chiba travel a breeze

Things to Do | Visit Chiba | Latest update:2023/06/05

Chiba, the place where you’ll likely be touching down if traveling to Japan, is located right next to Tokyo on the Boso Peninsula. While the northern side of Chiba is located right next to Tokyo, southern Chiba is separated from Tokyo by Tokyo Bay. This used to make the wonderful expanse of much of the peninsula difficult to access. A long time in planning, the Tokyo Bay Aqua-Line Expressway (the official name is the Tokyo Wan Aqua-Line Expressway) crosses Tokyo Bay, and takes hours off the trip to lower and central Chiba.

Tokyo, and Kanagawa below, are immensely crowded regions, and a trip to Chiba used to be all the way around the north side of the Tokyo Bay, not to mention a battle against the traffic being funneled the same way. Now that we have a straight shot across Tokyo Bay thanks to the Tokyo Bay Aqua-Line, traffic to northern Chiba has been reduced, and the wonders of Chiba are within reach, even for a day trip!

The space between Kawasaki City on the west of the Tokyo Bay and Kisarazu City on the east side is not terribly far, and a plan to connect them had been in the works since the 1960’s, with the work being completed over eight years between 1989 and 1997. With one of the longest underwater tunnels in the world and the longest bridge in Japan, it’s separated into two official sections: the Aqua Tunnel, and the Aqua Bridge. The underwater section, the Aqua Tunnel, is a lengthy 9.5 kilometers. After this section, you’ll reach the “Umihotaru” parking and service area, which is followed by the 4.4-kilometer Aqua Bridge leading into Kisarazu City of Chiba.

The “Umihotaru” (Lit. Sea Firefly) deserves its own recognition, as it’s a massive parking and service area built on an artificial island. It’s known officially as a “parking area” in Japanese, a term which refers to stops along expressways with restaurants and shopping, meaning despite the name, it offers more than just parking. Many make the Umihotaru a part of their trip, as along with lunch and some souvenir and snack shopping, you can relax on the observation deck with sweeping views of Tokyo Bay, and moreover, at the Aqua-Line Theater, be in awe at the amount of engineering genius that went into the Aqua-Line project which used the latest technology at that time. A great place to refresh and reflect before completing the journey into Chiba proper!

The sprawling and intertwined roads and tunnels of the Kawasaki side of the Aqua-Line is quite different from the Kisarazu side. As soon as you cross the Aqua Bridge into Chiba from Tokyo, it’s very apparent that you’ve crossed into a different world. You’ll see palm trees, and open expanses on either side of the road. The first stop off the Aqua-Line leads to Mitsui Outlet Park Kisarazu. This, along with the Umihotaru, are both popular first stops for many to kick off their Chiba adventure by car or bus.

You can of course take the train from Tokyo down to the major areas of Chiba, and use subsequent local lines, but the deeper you get on the peninsula, the more convenient it will be to have a car. We encourage you to give driving a shot, and moreover use the innovative engineering that is the Tokyo Bay Aqua-Line Expressway!

Sightseeing Spots

Tokyo Wan Aqua-Line Expressway (Umihotaru Parking Area)

A marvel of engineering, and a solution to convenient Chiba travel! The Tokyo Wan (Lit. Tokyo Bay) Aqua-Line Expressway connects Kawasaki City and Kisarazu City via an underwater expressway, and has one of the most unique service areas around: the Umihotaru! Take in the views of Tokyo Bay while you enjoy lunch and souvenir shopping here.

Umihotaru, Nakajima, Kisarazu City

(Access to Umihotaru Parking Area: 45 minutes by car or bus from Kawasaki Station, or 30 minutes by car or bus from JR Kisarazu Station. Note: trains do not operate on the Aqua-Line Expressway.)



  • Handicap parking
  • Handicap toilet
  • Ostomate restroom
  • Wheelchair rentals
  • Written communication for the hearing impaired
  • Wheelchair ramp
  • Stroller rentals
  • Breast-feeding room
  • Service dogs permitted
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