When we visited the Jigokudani Monkey Park in Japan last January I never gave a second thought to whether or how the hot springs the Japanese macaques bathed in got clean. I just figured it was a natural feature of their environment and one that was left to 'nature' to deal with.
However, after regularly clicking in to view the monkey park's web cam, I've learned that their hot springs pool does get cleaned — regularly. Every week, if not every other day. When I check in during the morning hours, Japan time, I frequently see the pool drained and workers mopping up.
That surprised me. The other thing that surprised me is that there are large rocks inside the pool that come nearly to the waters surface. So, the monkeys I saw hanging around in the center of the hot springs while I was there were not treading water, they were lounging on rocks!
The other thing that surprised me, after watching the monkeys via web cam off and on for the last 8 months, is that they still go down to the hot springs during the summer. I wouldn't have guessed that. The water is rather warm and Japan is a hot, muggy place during the summer. But these highlander monkeys do live in the mountains where it is always cooler.
Even if the monkeys can be seen there year round, I still think it is far superior to see them in the winter with snow all around. After all, they are nicknamed Snow Monkeys.