Japanese macaques in hot springs, Jigokudani Monkey Park, Japan

© Per-Gunnar Ostby/Getty Images

Japanese macaques in hot springs, Jigokudani Monkey Park, Japan

When the weather outside is frightful, the snow monkeys here at the Jigokudani Monkey Park in Japan descend from the forest and soak in the naturally occurring hot springs, known as onsen. Snow monkeys, more formally known as Japanese macaques, hold the distinction of being the northernmost living non-human primate. They are a sophisticated lot, known for washing their food before eating it, occasionally engaging in snowball fights and indulging in these warm baths. The macaques also make adorable poster primates for Monkey Day, celebrated each year on December 14.