Rainbow Pool (2014)

The vast Showa Kinen Park in Tachikawa hosts this massive complex composed of a total of nine pools, a four-lane water slide, wave machines and plenty of space to work on your tan. Crowding can get out of hand here especially on weekends, when you can sometimes barely manage to slip into the water without bumping into fellow swimmers. Claustrophobics may want to check out the rest of the park instead and enjoy its scenic bike paths and barbecue opportunities, available for use without any extra cost.