Jigokudani Monkey Park

The park lies at the head of the Yokoyu River valley, below the Shiga Kōgen highlands, at an altitude of about 850 metres. The name Jigokudani, 'hell valley', comes from the steam and boiling water that rise from the ground along the valley floor, including a hot-spring geyser just below the park. In winter the valley lies under a metre or more of snow, and temperatures drop well below freezing.

The Japanese macaque is the most northerly living non-human primate, and the troop here ranges freely through the surrounding forests. The park was founded in 1964 by a local man, Hara Sōgo, who opposed the culling of monkeys that were raiding apple orchards. Over three years he accustomed the wary troop to a site upstream, away from the farms, where food could be provided.

Soon after the park opened, young monkeys began bathing in the outdoor bath of a nearby inn, and adults followed. For hygiene a separate pool for the monkeys was built. The sight of macaques with snow-capped heads sitting in the steaming water became internationally known, particularly after the 1998 Nagano Winter Olympics, when the world's media covered the nearby snowboard venue.

In the early 1960s monkeys descending from the mountains damaged orchards in the area, and permission was given to shoot them. Hara Sōgo instead fed the troop further up the valley, and the park opened in 1964, run by a local company with the aim of showing coexistence between people and monkeys.

Bathing began as a habit copied from young monkeys and spread through the troop. Researchers have since studied it as an example of learned behaviour; later studies found that bathing helps the monkeys reduce stress and conserve heat in winter.

The park is a rare place where wild primates can be watched at a distance of a few metres, and it has become a subject of photography, documentary film and scientific research. It reflects a Japanese tradition of monkey observation parks (yaen kōen) that combine conservation, tourism and the reduction of conflicts with farmers.

The nearby hot-spring towns of Yudanaka and Shibu belong to the old onsen culture of northern Nagano, with narrow streets of wooden inns and public bathhouses. Many visitors combine the monkeys with a stay in these towns and the ski slopes of Shiga Kōgen.