For a totally Japan off the beaten path outing, you should visit Tokyo’s “G-Cans”, officially known as The Metropolitan Area Outer Underground Discharge Channel. This is so unique that most locals don’t even know about it, and much less that you can actually tour the facility.
This is one of the world’s largest underground storm water management facilities, spanning nearly four miles underground. There are five large “banks” or huge shafts that drop 70 meters from alongside several area rivers. These “banks” are each large enough to hold an entire Statue of Liberty. When storm waters rise, gates along the rivers open up and water flows into these “banks”, then into a four mile tunnel that is 30 meters in diameter.
From there, water flows into a cavernous storage tank called the Pressure Regulating Tank, or commonly called “The Cathedral” since that’s what it really looks like. Its like something out of a sci-fi movie because it has actually been used in many such movies. Its incredible to stand on the floor of this place, and only a few people know about.
There are four tour options, and all include visiting “The Cathedral”, while some focus on the “banks” and others on the pump station that has pumps that can drain “The Cathedral” at a rate of one Olympic sized pool in two seconds! There’s nowhere else in Tokyo to grab a selfie like here at the G-Cans. Tours are limited and everything is in Japanese, although there is an extensive English tour booklet, and honestly you’ll understand easily enough the scope of this place simply by being there. We highly recommend this as part of Uncharted Japan you should visit.