There's a reason macaques look so serene in their photos. Submerged up to their cheeks in steamy water with snow drifting onto their furry heads—they look almost meditative.

Researchers always suspected the monkeys used the hot springs to stay warm in the winter, and a new study published in the journal Primates confirms this. While the researchers suspected this was the case, the finding could still illuminate how the monkeys cope with stress.

Of all the primates in the world, Japanese macaques live the farthest north. For decades, they've been observed taking baths in Jigokudani Monkey Park in Japan. Their behavior has become so endearing to people that thousands of tourists often trek north to take a peak