Metropolitan Area Outer Underground Discharge Channel

"Shutoken Gaikaku Hosuiro"The Fruit of Japan's Technology; Underground Sanctuary

Outline "Shutoken Gaikaku Hosuiro" is the world's largest underground flood water diversion facility, built to mitigate overflowing of the city's major waterways and rivers during rain and typhoon seasons. The water it takes in goes to Edo River through the tunnel with a total length of 6.3km (3.9 miles), and with a 50 meter (164ft) tall lock (tank) which is deep underground. It was built in June, 2006, with Japan's world-leading forefront of construction technology.
The scale of Metropolitan Area Outer Underground Discharge Channel when it's fighting with flood without showing to anybody is just like a Guinness level.

It's just beyond imagination that it has huge five shafts with diameter; 30 meters (98ft) and depth; 70 meters (230ft) that take flood in, the bottom tunnel with diameter; 10 meters (33ft) that runs through 6.3km (3.9 miles) deep underground, a mammoth tank which has 59 soaring pillars with weight; 500t, and a turbine with 14,000 horsepower that drains water with 200 meters (656ft) cubed per a second.
To make a tour here, you must make a reservation. You can't make a reservation through Tourist Company or Travel Agency, so be sure that you make a reservation by yourself.