The snow monkeys of Jigokudani are famous for their enjoyment of the natural hot springs in the area. They bask in the waters, groom each other and relax, enjoying a respite from chilly winter temperatures.
It was heartening to see visitors behaving themselves and obeying the rules on the day we visited. Perhaps the trek to the site weeds out the more frivolous and uncaring. On the day that we visited the trail was extremely icy, and from memory it is at least a couple of kilometres long, so some dedication is required to make the journey. At the trailhead there is a shop selling cheap boots with soles that grip and gripping attachments you can fit to your own shoes.
Many websites recommend visiting the snow monkeys either by driving there or catching the train to Jigokudani (the end of the line) and then the shuttle bus. There are local and express trains that go to Jigokudani. The express train costs a little extra (there's an extra ticket to buy at the machine) but saves time. We took the train and shuttle bus found this is not actually a good method if you're travelling from Nagano, the closest town.
Tourist information sites state that the shuttle bus timetable roughly coincides with the train times. This isn't the case. When you arrive at the station, you may have to wait 45 minutes or so for a bus, which takes only about ten minutes to drive to the trailhead. Returning to the train station by the shuttle bus, you may have to wait a similar amount of time for a train.
A much faster and more convenient option is to take the bus that leaves from outside Nagano station and goes directly to a bus stop close to the trail head. This bus takes about one hour, as I recall. This is the method we used to return to Nagano.
Living in Taiwan, part of the pleasure of visiting the snow monkeys was simply the snow.
We had wrapped up warm, so the cold was no problem, and we could enjoy the novelty of the powdery white stuff.