YAMANOUCHI, Japan -- The scene is rugged. Cliffs jut up from around a snow-fed stream, then taper off into rolling evergreen forests and, farther off, into the frosted peaks of the central Japan Alps.
Picture at the center of it all a beautiful pool of clear, hot mineral water lined in dark gray rocks and surrounded by volcanic vents that spew up jets of pungent, sulfer-laden steam.
Now think of the movie Planet of the Apes.
Possibly nowhere in the world is a good soak in a hot spring more appreciated than it is in Japan. But at this resort in the heart of central Japan's hot springs country, the bathers are monkeys.
Here, macaques with thick, sand-colored fur and bright red faces sit in the water like caricatures of their human cousins, relaxing, nodding off. Some jump right in, others gingerly test the waters with a toe.
The bathing monkeys of Jigokudani, or Hell's Valley, are among the best-loved symbols of Japan's often forgotten wild side -- and there is probably not a more famous band of monkeys in the world.
The 250 macaques at this steaming ravine have their own live cam site on the Internet. They have been featured on stamps. They were a popular draw during the 1998 Nagano Olympics, when the snowboard half-pipe event was held just a 20-minute walk away.
Despite its relatively remote location and an economic slowdown that has soured tourism in Japan, roughly 90,000 visitors trek through the woods of Nagano each year to see Jigokudani Wild Monkey Park, according to park director Eishi Tokida.
What they find here is unique.
Jigokudani is as far north as it gets for monkeys. No primate, with the exception of humans, is known to live in a colder climate. And it does get cold here -- snow covers the ground for four months of the year, and winter temperatures average 14.
Though their thick fur can make them appear much larger, adult macaques average about 33 pounds in weight and stand about 2 feet tall. And though they are a relatively familiar animal throughout the mountainous areas of Japan, they are considered an endangered species.
What really makes them unusual, however, is their love of hot water.
"They started getting into the water about 40 years ago," says Harue Takefushi, the 90-year-old matron of Korakukan, a small wooden inn that has been here since 1864. "First came the little ones, then the adults. Then they started coming regularly to get out of the chill."
Today, the monkeys bathe in two main pools dug expressly for their use, or in the hot springs-fed stream that runs nearby. Though most seem to prefer to soak quietly, some submerge themselves to walk on the bottom of pools in search of nuts or other food.
In the colder months, it is not uncommon for the monkeys to use the outdoor bath at Korakukan as well.
"One guest ran away when some monkeys got in, but most of the people who come here enjoy it when the monkeys join them," Takefushi said. "The monkeys look so peaceful. I don't think they've ever attacked anyone."
That is also something of a rarity.
Overly aggressive macaques have become a major nuisance in several national parks and even in some city suburbs. In one town just south of Tokyo, roving bands of macaques regularly descend from the hills to steal food from grocery stores. Shopkeepers have fought back by brandishing pop guns.
Park director Tokida said the monkeys in Jigokudani are better behaved because they have an environment that provides them with ample food and enough room to roam freely. Overcrowding is a common problem in other monkey refuges in Japan.
Visitors to the park are discouraged from feeding the monkeys, and are asked to check their bags in lockers.