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Explore the Underground Sanctuary of Saitama’s Mysterious “Metropolitan Area Outer Underground Discharge Tunnel”, the Largest of Its Kind in the World

In recent years, with the increasing number of repeat visitors to Japan, a more pressing need has emerged to cater for this group with more tourist spots that are off the beaten track. This article introduces you to one such location, the Metropolitan Area Outer Underground Discharge Tunnel.

What Kind of Place Is the Metropolitan Area Outer Underground Discharge Tunnel?

Located in eastern Saitama's Kasukabe City, it is an underground water discharge tunnel situated 50m underground that extends for 6.3km. This facility is comprised of "collection systems" that take in water from rivers, underground water channels that store and transport water downstream, and drainage pump stations that discharge the collected water. Its unusual atmosphere and design has been featured in numerous films and TV programs, famously appearing in the film Tonde Saitama which opened in movie theaters in Japan on February 2019.

What Kind of Place Is the Metropolitan Area Outer Underground Discharge Tunnel?

720 Kami-kanasaki, Kasukabe-shi, Saitama

How to Get There

From Tokyo, it takes about one hour to get there and requires changing trains. It takes approximately 40 minutes to walk to the channel from the nearest station, Minami-sakurai Station on the Tobu Urban Park Line. Therefore, it is recommended to take the Aeon Mall Kasukabe bus (200 JPY for a one-way adult ticket) or a taxi (about 1,300 JPY).

Why Was Such an Enormous Underground Channel Created?

Kasukabe City and its neighboring towns and cities are surrounded by the Edo River and other massive rivers, forming a terrain resembling the bottom of a plate. This makes drainage especially difficult and during periods of substantial rainfall, it used to be prone to flood damage. This drainage channel was constructed in order to resolve this chronic flooding situation. Now, in times of large rainfalls, excess water from small and medium sized rivers are channeled underground and merged into the Edo River, preventing flooding. This prevents or lessens the risk of water damage to households.

Three Possible Tour Routes Around the Channels

The Metropolitan Area Outer Underground Discharge Tunnel is a world-class disaster prevention system. For parties who wish to know more about the systems and workings of the tunnel, as well as experience the enormous scale of the tunnel for themselves, how about participating in a guided tour? There are three different tour routes around the tunnel which will now be introduced in detail.

The Shaft Tour That Packs a Punch

On this course, you can tour a massive pit with a depth of 70m and diameter of 30m, known as Shaft Number 1. You will be able to do a full rotation of the specially created pathway used by workers in the tunnel (dubbed the catwalk) as well as descend the stairs inside the shaft to a certain point, giving you an opportunity to experience the full majesty and power of the tunnel to your heart's content. Moreover, you will also get to view the water pressure regulation tank that calms the flow of the water that flows down from the underground tunnels. The scale of the pillars and open spaces here gave rise to the name "Underground Sanctuary".

Tour capacity: 20 people
Length: Approximately 100 minutes
Price: 3,000 JPY per person
※Note: Participation in this tour requires you to wear a helmet and safety harness.

Explore the Depths! The Pump Tour

This tour was created around the pumps that form the heart of the water discharge tunnel. The workings of the pumps will be explained via a model, and through a tour of the pump room, you will deepen your understanding of the role and workings of the pumps. You can also see a special exhibit of the gas turbines, however, please note that this is not open to viewing while the pumps or tunnels are in operation. This tour is particularly recommended for machine enthusiasts. You can also see the water pressure regulation tank.

Tour capacity: 20 people
Lenth: Approximately 100 minutes
Price: 2,500 JPY per person

For a More Relaxed Experience, Choose the Underground Sanctuary Tour!

This tour packs the two most popular attractions - the water pressure regulation tank and the massive Shaft Number 1 - into 60 minutes. This tour's selling point is that it allows you to take in two of the most popular attractions in a comparatively short period of time. On this tour, you not only are afforded the opportunity to walk the catwalk, but you can also take in the view from the Viewpoint. Rest assured, the view point is suitably located at a distance to allow you to fully enjoy its incredible scale.

Tour capacity: 50 people
Length: Approximately 60 minutes
Price: 1,000 JPY per person

Reserving a Guided Tour

Bookings for tours are taken from the same day of the month prior to the month in which you wish to partake in the tour. For example, if you wish to take a tour on August 10th, you can reserve it from the 10th of July. If there is no same day in the previous month, then reservations open on the previous day of the previous month and can be made by the end of the previous day (11:59 pm). Reservations can be made online or by phone. Please check in at the tunnel adjacent to the 龍Q館 (Ryu Q Kan) between 10 and 30 minutes before the start of the tour. If you are late, then you will not be able to participate in the tour.

Reservation Page
※Before making an online reservation, be sure to read the guidelines. These are available in Japanese only.

Telephone number for reservations: +81-48-747-0281

Multilingual Support

Guided tours are provided in Japanese only. Please be aware that you will need to bring someone with you who can interpret for you. The tunnels do not provide interpreters for hire.

Please be aware that the routes taken on all tours may be subject to change at times when the facility is in operation. There are no changes to tour fees or refunds offered when this happens.

*Please note that the information in this article is from the time of writing or publication and may differ from the latest information.

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