If you’ve already seen Tokyo’s most famous tourist attractions, you’ll want to set your sights on some of the more remote locations in and around the capital. One such spot is the otherworldly Metropolitan Area Outer Underground Discharge Channel in Kasukabe, Saitama prefecture.
Affectionately known as the Disaster Prevention Underground Temple, the tunnel is a whopping 50 metres underground and is used to prevent flooding in the Greater Tokyo area during a major natural disaster such as a tsunami or typhoon. When not in use, the massive tunnel is open to the public for viewing. Its towering architecture has made it a popular spot for visitors – it has even been used as a filming location for music videos and other projects.
The best way to explore the Disaster Prevention Underground Temple is by joining a guided tour, such as the Underground Temple Course, which costs just ¥1,000 per person and takes about 55 minutes. On the tour, you can learn about the facility and explore at your own leisure.
Longer tours are available, too, including the Pit Experience Course (¥3,000 for 110 minutes) for a visit to the drain's 70m-deep shaft. There's also the Impeller Exploration Course (¥4,000 for 110 minutes) for those who want to explore the pressure regulating tank.
The newest of these tours is the Underground River Walking Adventure Course (¥15,000 for 240 minutes), where you can explore previously off-limits areas, including walking through an underground river with waters around 50 centimetres deep.
Do note that all tours are conducted in Japanese and will be cancelled in the event of sudden weather changes.
The storm drain is approximately 30 minutes on foot from Minami-Sakurai Station, but can also be accessed via community buses from the north exit of the station (just get off at the Ryukyukan stop).
If this underground tunnel sounds like your kind of excursion, you can find out how to book a tour on the website.
This article was published on December 8 2021 and updated on April 25 2025.
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