Construction of Tokyo’s massive flood tunnels began in 1993 and by 2006, the Metropolitan Area Outer Underground Discharge Channel was complete. Designed to protect the city from overflow, heavy rainfall, and typhoons, the water is then pumped into the nearby Edogawa River.
At maximum capacity the Channel can store 670,000 cubic meters of water, and has reduced flooding in low-lying Tokyo by 80%. It’s also known as the “Underground Temple” and is used as a film location.