Umihotaru: The Sea Firefly in the Middle of the Ocean in Japan

Traveling to Japan, it can be rather overwhelming to select the places that one would go to. With so many cities and attractions Japan has to offer, one would ideally want to go to all of these places. One of the most popular places that are visited by millions of foreign tourists every single year is the Tokyo Metropolis. However, due to its massive size, one would still have to choose only a certain portion of Tokyo to visit if one is on a limited time or budget. If one is interested in visiting a unique place near Tokyo, one would like to recommend going to Umihotaru.

Tokyo Bay Aqua-Line: Connecting Tokyo/Kanagawa and Chiba

By hokkane4 [CC BY-SA 2.0 (https://creativecommons.org/licenses/by-sa/2.0)], via Wikimedia Commons

Umihotaru is primarily linked to the Tokyo Bay Aqua-Line. More commonly known as Tokyo-wan Akua-rain in Japanese, Tokyo Bay Aqua-Line is a combination of a bridge and a tunnel. Also known as the Trans-Tokyo Bay Highway, it spans across Tokyo Bay. It serves as the link between the city of Kisarazu located in Chiba Prefecture and the city of Kawasaki located in Kanagawa Prefecture.

This famous highway plays an integral role in the fame of Umihotaru. It is a part of National Route 409. With a total length of 14 kilometers, this highway is composed of a bridge spanning about 4.4 kilometers and a tunnel spanning 9.6 kilometers. Located underneath the bay, its tunnel is the fourth longest underwater tunnel on Earth.

With the coordinates of 35°27’47” North and 139°52’31” East, this bridge carries four lanes of National Route 409. Its locales are Umihotaru Island and Kisarazu, Chiba. The bridge is a steel box girder type with orthotropic deck. The highway is also characterized by a bored shield tunnel and by artificial islands.

The bridge has a specific length of 4,384 meters, which is equivalent to 14,383 feet, while the tunnel is equivalent to 31,496 feet. The width of the highway is 22.9 meters, which is equivalent to 75 feet. The longest span of the bridge is 240 meters, which is equivalent to 787 feet. It also consists of 42 piers submerged in the waters of Tokyo Bay. The clearance below is 29 meters, which is equivalent to 95 feet.

The bridge was fabricated by Yokogawa Bridge Corp. and JFE Engineering. Its construction began in the year 1989. Because of its massive size and capacity, the construction cost of this line was 1.4 trillion yen at the time, which was equivalent to around 11.2 billion USD. This infrastructure was opened to the public on the 18th of December in the year 1997.

As for the Tokyo Bay Tunnel, it begins at Umihotaru Island and ends at Ukishima, Kawasaki, Kanagawa Prefecture. The tunnel was constructed by Taisei. It consists of 2 unidirectional lanes in each of the two tunnels while another tunnel is being planned at present. Its highest elevation is at sea level while its lowest elevation is 45 meters, which is equivalent to 148 feet, below sea level.

The outer diameter of the tunnel is 14.1 meters, which is equivalent to 46 feet, while its inner diameter is 11.9 meters, which is equivalent to 39 feet. The width of its roadway is 10.5 meters, which is equivalent to 34 feet. The tunnel also has a grade of 4 percent. Because of the Tokyo Bay Aqua-Line, the drive between Kanagawa Prefecture and Chiba Prefecture was significantly reduced. From having to drive for 90 minutes, the time was reduced to only 15 minutes.

Because the tunnel is built below sea level, the air inside the tunnel must be supplied manually. A tower located in the middle of the tunnel known Kaze no To supplies this much-needed air. Translating to “the tower of wind,” Kaze no To utilizes the winds in the bay as its source of power. Planning of the bridge and the tunnel took 23 years while its construction took 9 years before it was finally opened to the public.

Introducing Umihotaru: The Parking Area in the Middle of Tokyo Bay

By English: Abasaa日本語: あばさー [Public domain], from Wikimedia Commons

At the crossover point of the bridge and the tunnel lies Umihotaru Island, which is an artificial or man-made island. Literally translating to “sea firefly,” this island serves as a rest area that houses several restaurants, stores, and various amusement facilities. Also known as Kisarazu artificial island, Umitoharu Island has a length of 650 meters. Surrounded by water, it provides a rather picturesque view of the bay.

Standing on the island is the Umihotaru Parking Area. Even by international standards, this parking area is rather unique. A five-story building, the structure offers parking spaces from the ground level up to the 3rd floor. Its 4th floor and 5th floor are filled with commercial facilities. Quite popular even among foreign tourists, the Umihotaru Parking Area is the only shopping mall in the middle of the ocean that offers a 360-degree view of the bay.

Visiting Umihotaru begins as visitors get out of the tunnel. They are welcomed by the view of not just the small buildings in Umihotaru but also by Yokohama Landmark Tower and the Yokohama Bridge. A plus is the huge Mount Fuji serving as the background of this picturesque view.

On windy days, expect the sea to produce high waves. Should it be during the winter season, visitors must take note of the extremely cold winds that are expected to hit the artificial island. Hence, proper winter attire is a must. For people who like to be indoors, they can stay inside the shopping mall and just enjoy the views of the ocean. However, if one would like to feel the wind waving through one’s hair, one can stay in the outdoor area of the mall.

There are several attractions to see in Umihotaru. Probably the most popular one is the boring wheel, which was the one that was utilized to dig the tunnel underneath the sea. It took decades of research for the possibility of constructing a road connection in the middle of the bay. The Tokyo Bay Aqua-Line is considered by some to be the best non-performing asset in the country. Cars of normal size can cross the bridge for 3,000 yen. If one is using an ETC card to cross, there is a discount for the cost.

Another must-see in the island is Umimegane. A technical museum, Umimegane can be reached from the 3rd floor of the building going towards the side of Chiba Prefecture. The museum features the engineering technology that was incorporated in the construction of the bridge and the tunnel. Techniques used to make the Tokyo Bay Aqua-Line possible are also featured in this museum. This includes the different types of soil that were brought in from various prefectures.

A Guide to the Different Restaurants in Umihotaru

By English: Abasaa日本語: あばさー [Public domain], from Wikimedia Commons

Though there are stores in Umihotaru Parking Area that one can shop in, it is the restaurants that are actually quite popular. Restaurants can be found on the 5th floor of the building. If one is craving for some fresh seafood, definitely try Kisarazu-An. It obtains its seafood fresh from Boso, Chiba. It is open from 11 AM to 9 PM on weekdays and from 8:30 AM to 10 PM on weekends and holidays. Breakfast menu is only available from 8:30 AM to 11 AM. It accepts group reservations and features an ocean view.

However, if one is looking for a place that offers ramen, the place to be is Menya Riku kara 5-kiro Ken. It is open from 11 AM to 9 PM on weekdays and from 11 AM to 10 PM on weekends and holidays. It offers meal tickets as well as an ocean view. For Hawaiian and other cuisines, check out Ocean Kitchen. It is open from 11 AM to 9 PM on weekdays and from 8:30 AM to 9 PM on weekends and holidays. It also accepts group reservations and features an ocean view.

If sushi is what one is looking for, head on over to Kaisen Misakiko. It is open from 11 AM to 9 PM on weekdays and from 11 AM to 10 PM on weekends and holidays. Similar to most of the restaurants on its floor, it also accepts group reservations and features an ocean view. On the 1st floor lies a food store that offers soba and udon among others. Called Kazusa Soba and Udon, this food shop open from 7 AM to 6 PM on weekdays and 7 AM to 8 PM on weekends and holidays.

Aside from the restaurants located on the 5th floor, there are also various food establishments that can be found at the food court. The food court occupies certain spaces on the 4th floor and the 5th floor. Some of these food establishments include Asariya, Marine Sweets, Sasebo Burger, Nami-Ichi, Umikaze, Ushio-Tei, Cheeba-Don, and Tendon Tenya. Some of them offer an ocean view while others do not. They offer dishes that are great and at an affordable price.

Ways to Go to Umihotaru

By aotaro (Tokyo Bay Aqua-Line Highway) [CC BY 2.0 (https://creativecommons.org/licenses/by/2.0)], via Wikimedia Commons

There are many ways to go to Umihotaru. The first option is to travel by car. Coming from the area of Tokyo, Yokohama, or Kawasaki, one shall take the Tokyo Bay Aqua-Line, which links to the National Route 409 and the Bayshore Route at the Ukishima interchange and the Kawasaki Ukishima intersection. Coming from the area of Chiba or Kisarazu, one shall take the Tokyo Bay Aqua-Line, which links to the National Route 409 and the Aqua Renraku Expressway at the Kisarazu Kaneda junction. Aqua Renraku Expressway serves as the link between the Tateyama Expressway and the Ken-O Expressway.

If one would not eventually be going to the other side of the bridge, one can just turn back at Umihotaru. Turning back, visitors would be charged a one-way toll fee. From the side of Kawasaki, visitors can return either by using ETC or by paying cash. Visitors utilizing ETC can take the ETC lanes so long as they are driving on ETC wireless drive mode, which means that the ETC card is inside the onboard unit. Visitors paying cash would just have to follow the signs leading to Kawasaki. Upon reaching the Umihotaru toll booth, simply pay the amount required and be on one’s way.

From the side of Kisarazu, visitors can also return either by using ETC or by paying cash. Visitors utilizing ETC can take the ETC lanes so long as they are on ETC wireless drive mode. Upon reaching the Kisarazu toll, simply take an ETC lane to pass through. As for visitors paying cash, one’s Aqua Line toll was already charged when going to Umihotaru at the Kisarazu Kaneda junction. Hence, one would no longer have to be charged for the return trip.

Simply follow the signs leading to Kisarazu. Upon reaching the turn-back certificate machine, obtain one’s certificate before following the signs leading to the Kisarazu Kaneda interchange. Return the turn-back certificate to one of the attendants manning a toll booth. After which, one can already be on one’s way going home.

Another option in going to Umihotaru is by taking a transit bus. Transit buses are available from both Kawasaki station and Kisarazu station. Depending on the day of the week, departure times may be different. The best way to take the bus is by knowing when the departure time is before beginning one’s trip is one would not be too early or too late.

For buses heading to Umihotaru, there are two bays to keep in mind. Coming from Kisarazu, the stop is at Bay 7 located at Kisarazu station. Coming from Kawasaki, the stop is at Bay 22 from the east exit of Kawasaki station. Heading home, there are also transit buses available at Umihotaru. Departing for Kawasaki, take the bus at the Kawasaki side of the parking area on the first floor. Departing for Kisarazu, take the bus at the Kisarazu side of the parking area on the first floor. Take note of the bus schedule so as not to miss the last departure of the bus.