Metropolitan Area Outer Underground Discharge Channel

Maybe it’s because the Teenage Mutant Ninja Turtles are making a comeback, but there’s something thrilling about venturing into this world of tunnels. This massive surge tank, known as the ‘underground temple’, was completed in 2006 and is the world’s largest underground flood water diversion facility. It’s made up of five shafts approximately 70 metres high, which are connected by a 6.3km tunnel; a pressure-controlled water tank; and 59 huge pillars, which are linked to pumps that direct water into the Edo River. It was built because the area around this structure collects water very easily, leading to flooding every time there’s heavy rain. Now, when the area floods, rainwater drains into the underground discharge channel and gets pumped up into the river. Because of its mysterious atmosphere, the structure is often used for music videos and photo shoots, and has become an unlikely tourist attraction as guided tours explain what happens when the worst happens. If your Japanese isn’t up to par, note that you’ll need to ask a Japanese-speaking friend to accompany you or make friends with somebody there – it’s a health and safety thing. Speaking of which... as you’d expect no visitors are allowed on days of heavy rain.