One of the world’s largest underground discharge channels, this facility was built to protect the low-lying areas of eastern Saitama Prefecture from repeated flooding caused by heavy rain. This massive flood control system diverts rising water from small and medium-sized rivers, including the Nakagawa, Kuramatsu, and Ootoshi-Furutone rivers, into an underground tunnel that runs 3.9 miles before discharging it into the Edogawa River.
Rising river water flows over weirs built into the river embankments, down enormous cylindrical shafts connecting the surface to the underground system, and through a tunnel 164 feet below ground before reaching the pressure-regulating water tank. From there, massive pumps discharge the water into the Edogawa River. The tank is an immense space measuring 581 feet long, 256 feet wide, and 59 feet high, with 59 pillars supporting the ceiling. Its resemblance to a vast temple beneath the ground has earned it the nickname “Underground Temple for Disaster Prevention.”
The facility normally operates only a few times a year, and tours are offered when it is not in operation. There are three options: the Impeller Exploration Course, which takes 110 minutes; the Shaft Experience Course, which takes 110 minutes; and the Underground Temple Course, which takes 60 minutes. All three include an introduction to how the Metropolitan Area Outer Underground Discharge Channel works and a visit to the pressure-regulating water tank, also known as the Underground Temple. Details of each itinerary are available on the official website, making it easy to choose one based on your schedule and interests. Advance reservations must also be made through the website.
Highlights
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Explore the mysterious “Underground Temple,” which has also been used as a filming location.
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Gain a deeper understanding of flood control.
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Visitors must be able to climb approximately 100 steps without assistance to tour the pressure-regulating water tank.
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The facility is far from the nearest station, and buses are very infrequent, so taking a taxi is recommended. Because few taxis are available at Minami-sakurai Station, many visitors reserve one in advance or take a taxi from Kasukabe Station.
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Tours may be changed or canceled when the facility is in operation.
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