Tokyo Flood Prevention | Insane underground tunnel system in Japan!

Fifty metres under Tokyo lies a subterranean world — 6.4 kilometres of tunnels, water tanks and massive pillars constructed to withstand 200 tonnes of water per second. This engineering marvel built to protect the ever-present threat of Tokyo flooding. Subscribe to ABC Science YouTube 👉 https://ab.co/2YFO4Go Australians can watch Catalyst on ABC iview: http://iview.abc.net.au/programs/cata... This is an official Australian Broadcasting Corporation YouTube channel. ******** Contributions may be removed if they violate ABC's Online Conditions of Use http://www.abc.net.au/conditions.htm (Section 3).