Jigoku­dani Mon­key Park is a famous hot spring area near Nagano, Japan. The name Jigoku­dani (mean­ing “Hell’s Val­ley”), is due to steam and boil­ing water that bub­bles out the frozen ground, sur­round­ed by steep cliffs and for­mi­da­bly cold and hos­tile forests.

It is famous for its large pop­u­la­tion of wild Snow Mon­keys that go to the val­ley dur­ing the win­ter when snow cov­ers the park. The mon­keys descend from the steep cliffs and for­est to sit in the warm waters of the onsen (hot springs), and return to the secu­ri­ty of the forests in the evenings.