Tokyo Bay Aqua Line

Japan City Guides: Tokyo Bay Aqua Line

Tokyo Bay Aqua Line 東京湾アクアライン

by Johannes Schonherr

Planes flying into Tokyo's Haneda Airport typically fly a loop over the southern Boso Peninsula in Chiba Prefecture before heading in a straight line over Tokyo Bay and right onto the landing strips of the airport.

Tokyo Bay Aqua Line, Japan.
Driving the Aqua Line Bridge towards Chiba, Tokyo Bay Aqua Line Bridge

Looking out of the of the airplane window during the final descent, you see a strange structure down in the bay: a long bridge starting out from the Chiba side of the bay, covering about a third of the distance to Tokyo, then suddenly stopping at a tiny island.

All other sides of the island are surrounded by water. Where do the many cars traveling the bridge go? The answer is easy: into a tunnel. What you are seeing from the plane is the above-ground part of the Tokyo Bay Aqua Line (aka the Trans-Tokyo Bay Highway).

Tokyo Bay Aqua Line, Japan.
Tokyo Bay Aqua Line Bridge

Driving the Aqua Line

The Aqua Line is a 4-lane highway connecting Kawasaki City, Kanagawa Prefecture with Kisarazu City in Chiba Prefecture.

Kawasaki City is just south of Tokyo, several highways from Tokyo, Yokohama and Kawasaki itself converge just before the entrance to the Aqua Line.

Coming from Kawasaki, you pass at first through a landscape of industrial plants, all built on reclaimed land. It is a bizarre view. Factory after factory, all of them seemingly just systems of steel, pipes and smoking chimneys stretching into the air. Truck traffic is heavy here.

There is no toll booth on the Kawasaki side. The highway takes you straight to the entrance of the Aqua Line Tunnel. A sign in front of the tunnel informs that the tunnel is exactly 9,610 meters long, which makes it one of the longest undersea tunnels in the world.

The tunnel is brightly lit and spaciously built. About half-way through, signs indicate the Kaze no To, the Tower of Wind.

That's not a point to stop, just an information that you pass below that tower which, as its name suggests, supplies fresh air to the tunnel, powered by the almost constant winds of the bay.

When you reach daylight again at the end of the tunnel, you drive onto a small artificial island called Umihotaru (which translates as "Sea Firefly").

The island hosts a five-story building, the Umihotaru rest stop.

Shaped in the form of a ship, the lower three stories of the Umihotaru rest stop are parking areas while the two upper floors house a variety of restaurants, souvenir shops and viewing platforms.

On Umihotaru Island, the Aqua Line transforms from a tunnel to a bridge, spanning another 4km over Tokyo Bay before arriving on land in Kisarazu City, Chiba. That's the bridge you can see from the airplane.

Tokyo Bay Aqua Line, Japan.
Tokyo Bay Aqua Line, Kawasaki Tunnel Entrance
Tokyo Bay Aqua Line, Japan
Umihotaru Island


Many of the drivers out on the Aqua Line for touristic rather than professional purposes choose to do a stop at the Umihotaru rest house.

In clear weather, the viewing platforms on the 4th and 5th floor offer great views over the whole Tokyo waterfront. The Tokyo Skytree clearly stands out. The skyscrapers of downtown Yokohama are also clearly visible.

On good days, Mount Fuji will tower right behind Yokohama. Half-way towards the industrial facilities of Kawasaki, you will see a strange cone rising from the sea. That's the Kaze no To, the Tower of Wind, that provides the Aqua Tunnel with air.

Many ships pass through between the island and Kawasaki, often huge cargo liners going to or coming from the harbors in Tokyo Bay. One airplane after another can be seen descending towards Haneda Airport, just north of Kawasaki.

Outdoor stairs lead down from the 5th floor to sea level. From there, the views are just as amazing. A huge monument stands close by the sea. It looks like a giant piece of abstract art but actually, it's the drilling surface of one of the machines used in carving the Aqua Line Tunnel.

Construction of the Aqua Line started in 1989, it opened for public traffic in 1997. Umihotaru with its rest house dates from the same time.

The 4th and 5th floors of the rest house offer a great variety of restaurants. Local seafood is on offer as is conveyer-belt sushi, ramen, soba and udon noodles, Chinese dumplings, tempura rice bowls and so on. Sasebo Burgers are available at the food court on the 5th floor. For a full list of the restaurants and shops, including opening times, see the English-language Umihotaru website.

Definitely a curiosity to see is the man's room on the 4th floor (sorry, ladies). Four urinals are facing a glass wall offering a grand view over the Tokyo Bay while you are doing your business. It's quite a bizarre sight walking into the room and seeing men lined up there in front of the sea.

Walking over to the eastern section of the Umihotaru, you get a spectacular view over the bridge spanning from the island to Kisarazu, Chiba. Going over that bridge will be your final part of the Aqua Line Tunnel drive.

On the Kisarazu side wait the toll booths. If your car is equipped with an ETC electronic toll collecting card system, 800 yen will be deducted from your bank account for the drive with a regular car.

Bad news awaits drivers paying cash: for them, it's a whopping 3090 yen. One way. See more on the toll details below.

Tokyo Bay Aqua Line, Japan.
Umihotaru Rest House, Tokyo Bay Aqua Line
Tokyo Bay Aqua Line, Japan.
Upper Deck, Umihotaru Rest House, Tokyo Bay Aqua Line

Tokyo Bay Aqua Line By Bus

It is possible to travel the Aqua Line by bus. You can leave the bus and explore Umihotaru and then either continue on to Kisarazu or return to Kawasaki by riding another bus.

Buses leave from Kawasaki Station and, on the opposite end, from Kisarazu Station. The Umihotaru website provides basic information in English. Unfortunately, the bus company website listing departure times and prices is only in Japanese.

A trip for an adult from Kawasaki to Umihotaru will be 1080 yen one way, a trip to Kisarazu 1440 yen one way.

Buses are frequent during daytime. Please be aware, however, that not all buses stop at the Umihotaru. This is especially the case for morning and evening buses. According to the current schedule, the last bus back to Kawasaki from Umihotaru will leave at 5.56pm, the last bus going to Kisarazu at 5.29pm. Thus, there is not much of a Tokyo skyline night view from Umihotaru to enjoy if you go by bus.

Tokyo Bay Aqua Line, Japan.
Umihotaru view towards the bridge spanning to Chiba

The Umihotaru website offers plenty of information on the island rest house in English.

Detailed information on highway tolls, bus prices and schedules are however given only via link to Japanese-language sites.

Highway tolls: Small car and motorcycle: 2,460 yen (with ETC card 640 yen), regular car 3,090 yen (with ETC card 800 yen), large car and van 3,700 yen (with ETC card 960 yen), truck 5,090 yen (1320 yen), oversize truck 8,490 yen (with ETC card 2200 yen).

It is possible to just drive to Umihotaru and make a U-turn there. In that case, you are charged a one-way toll at Umihotaru.

During typhoons and other heavy storms, the Aqua Line is closed. Check local weather information before going.

Tokyo Bay Aqua Line on google maps

Tokyo Bay Aqua Line, Japan.
View from the Umihotaru towards Tokyo, the cone in the sea on the left is the Kaze no To (Tower of Wind)
Tokyo Bay Aqua Line, Japan.
Exhibit on Umihotaru. This is not abstract art, it's part of a machine used to dig the Aqua Line Tunnel

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