Jigokudani Monkey Park is located in Yamanouchi, Nagano Prefecture, Japan, about 3.5 hours from Tokyo. It is part of the Joshinetsu Kogen National Park, and is located in the valley of the Yokoyu-River, in the northern part of the prefecture. The name Jigokudani, meaning "Hell's Valley", is due to the steam and boiling water that bubbles out of small crevices in the frozen ground, surrounded by steep cliffs and formidably cold and hostile forests.