Staring into a pitch-black void. Wading through knee-deep, stagnant water. Dangling a camera over a railing above a concrete abyss deep enough to comfortably fit the Space Shuttle, praying that you can grab a photo without losing your grip.

These are just some of the joys of touring the Metropolitan Area Outer Underground Discharge Channel, ostensibly a critical part of the capital region¡¯s defenses against severe weather events but perhaps the greater Tokyo¡¯s areas most unique tourist attraction.

From April 16, the facility will be conducting of areas previously unavailable to the public: For ?15,000, the new Underground River Walking Adventure Experience Course will bring visitors down to the bottom of the discharge channel¡¯s 70-meter-deep, 30-meter-diameter No 3. shaft, one of five concrete silos used to contain surging waters from the Kuramatsu, Naka and other small- to medium-size rivers that have flooded the surrounding region throughout history.