In just about an hour from Tokyo by shinkansen train you will find the beautiful city of Nagano. A short bus trip from the train station will take you to the Jigokudani Yaen-koen. It is located in the Valley of Yokoyu River sourced from Shiga-Kogen of the Joshinetsu-Kogen National Park in the northern part of Nagano prefecture.
Because of the very steep cliffs and the steam coming off the springs everywhere, ancient people called this valley ‘Jigokudani (Hell valley)’. Also, it is buried in snow almost one-third of the year. Even that severe environment here is a paradise on earth for monkeys to live in. The troops of wild Japanese macaques (popularly known as snow monkeys) naturally inhabit there through the ages.
Since the establishment of Jigokudani Yaen-koen in 1964, it has been a worldwide popular place for watching the bathing monkeys in a hot spring and for ecological observation by researchers and photographers. I visited it on my last trip to Nagano and took a few photos myself:
I know, monkeys are adorable, but also you need to be very careful around them after all they are wild animals. They tend to steal things from bags or pull items from the pockets of unsuspecting visitors so you have to keep your personal belongings secure when you are there. But it was an amazing experience and I highly recommend coming here to see them.