Translated by Jasmine Nishino
Simply Amazing! Tokyo's Metropolitan Area Outer Underground Discharge Channel
Written by Otsuji
The largest underground water diversion facility in the world, the Metropolitan Area Outer Underground Discharge Channel, located in Saitama, is known as an ”underground temple” due to its unique structure.
Did you know there was a place referred to as the ”underground temple” in Saitama? It is an industrial facility managed by the Ministry of Land, Infrastructure, Transport and Tourism, but the beautiful structure has gained fame and has been used in many TV shows, films, and even featured by media outside of Japan.
This time, we would like to introduce you to the city's underground labyrinth, the Metropolitan Area Outer Underground Discharge Channel. You can visit the facility for free, so it is a great place to visit while touring around the city!
*Please note that reservations will be needed in advance. Guidance on how to make reservations is provided later in this article.
What is the Metropolitan Area Outer Underground Discharge Channel?
The Metropolitan Area Outer Underground Discharge Channel is a flood prevention facility located in Kasukabe city in Saitama. With areas below sea level, this area has suffered many floods for a long time.
In order to prevent this from happening again in the future, they decided to create the Metropolitan Area Outer Underground Discharge Channel to transport the floodwater to an underground tunnel from which it can be diverted and drained out to a safer and larger river. Kasukabe city in Saitama had been undergoing an urbanization process and was thus selected to house this discharge channel in a massive space underground.
Explore the Labyrinth!
At the Metropolitan Area Outer Underground Discharge Channel, a 60-minute tour is available for those who make reservations in advance.
The tour starts at the meeting point, the RyuQkan. Your guide will be explaining to you about the history and reasons behind the construction of the underground discharge channel using a map.
*For tours starting at 15:00, a simple explanation will be given on the first floor using panels.
Further details will be shown through informative videos and models where you can see the water flow. Here, you will get a further understanding of the purpose and the structure of the underground discharge channel.
This is the central command center where people keep an eye on the facility as they also monitor the weather. This is also where they control whether to run or stop the facility as well.
On To The Underground Temple Adventure
After understanding the purpose and the structure of the Metropolitan Area Outer Underground Discharge Channel, you will head into the area referred to as the underground temple. This is actually a ”water pressure regulation chamber” where the pressure of the water from the underground tunnel is eased before being smoothly released from the facility.
As you will be heading down nearly 100 steps underground, you should wear a comfortable pair of sturdy shoes.
* For safety reasons, you cannot participate in this tour if you are wearing high heels or sandals.
The moment you reach the bottom, you will find yourself within a colossal structure. The sheer massiveness may overwhelm you a bit at first.
This enormous underground space is 78 meters wide and 177 meters deep. The 59 pillars, standing 18 meters high and each weighing 500 tons, hold up the ceiling of this underground temple.
When a person stands next to the pillar, you can see just how massive it is in comparison.
This is the facility called Daiichi Tateko (vertical well number 1). It takes in the water that over flows from the river and leads to the underground tunnel.
This time, we visited as reporters, therefore were able to visit this special spot to look into the vertical well from above. This well is nearly 70 meters deep and has a radius of 30 meters. It is an enormous facility that can easily fit a space shuttle or even the Statue of Liberty.
After exploring inside for about 20 minutes, the tour comes to an end. This massiveness cannot be adequately expressed through photos alone. The Metropolitan Area Outer Underground Discharge Channel is a place that you just have to see with your own eyes.
How to Get to the Metropolitan Area Outer Underground Discharge Channel
The closest station to this facility is Minami Sakurai Station on the Tobu Noda line. To get to the underground discharge channel, it is nearly a 40-minute walk from the north exit, so taking a taxi is a good idea. From Minami Sakurai Station’s North exit, it will take approximately 7 minutes (costing around 1300 yen) by taxi.
Just tell the driver to drop you off at the RyuQkan. Once you arrive, head to the check-in spot on the second floor of the RyuQkan. From Minami Sakurai Station North Exit, there is also a Kasukabe city community bus, the Haru bus, which travels to RyuQkan as well, but its operational days and times are very limited.
Reservations for Visits
The Metropolitan Area Outer Underground Discharge Channel holds three tours daily from Monday to Friday every week for free. On occasion they hold tours on Saturdays as well. For more details, please check the notifications regards visits (Japanese only). The RyuQkan is closed on Mondays and only accepts group visits (1 group of 26-50 people only).
Tours also require reservations in advance as well. You can reserve online or by phone. Please read the Metropolitan Area Outer Underground Discharge Channel website for more details.
Please keep this in mind when visiting.
Explanations and instructions are given verbally in Japanese only. For safety purposes, you will need to be accompanied by someone in your group who understands Japanese (interpreter, sign language interpreter, etc.). If you do not understand Japanese, ask someone you know or hire a professional interpreter to join this tour.