Jigokudani Monkey Park is located in Yamanouchi, Nagano Prefecture, Japan. It is part of the Joshinetsu Kogen National Park (locally known as Shigakogen), 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.

It is famous for its large population of wild Japanese macaques (Macaca fuscata), more commonly referred to as snow monkeys, that go to the valley during the winter, foraging elsewhere in the national park during the warmer months. 

- Wikipedia