Tokyo’s Underground Discharge Channel

The Metropolitan Area Outer Underground Discharge Channel (Japanese: 首都圏外郭放水路, shutoken gaikaku hōsuiro), is an underground water infrastructure project in Kasukabe, Saitama, Japan. [4]

“Ryukyukan” for Underground Exploration Museum of The Metropolitan Area Outer Underground Discharge Channel is also a tourist attraction and can be visited for free; however, as the tours are conducted in Japanese, a Japanese speaker must be present in the group to act as a translator for non-Japanese speakers. In 2006, a Land Rover television commercial and print campaign was produced using Metropolitan Area Outer Underground Discharge Channel as a location.

Source: en.wikipedia.org