At 133m, Nachi-no-taki is Japan's highest waterfall. It's the first of many still deeper in the Nachi mountains and has long been used in ascetic training.
For a close-up look at the falls, hike the 135 steps to a small shrine, Hirō-jinja, which has a viewing platform (it's also the spot from which to worship the falls). Drinking water from the dragon's mouth at the font (use your hands as a bowl) is believed to enhance longevity.