The macaques of Jigokudani did not learn to bathe from their ancestors. The habit began around 1963, when a young female followed an apple into the open-air bath of a nearby ryokan and stayed. Others copied her. Within a generation, hot-spring bathing had become cultural behaviour transmitted through the troop — one of the few documented cases of a wild primate tradition arising in living memory. The valley itself is older than the habit. Jigokudani, written with characters meaning "hell valley," earned its name from the sulphurous steam that vents through the snowpack along the Yokoyu River, roughly 850 metres above sea level in the Joshinetsu Kogen highlands. Local people avoided it. Foresters worked the slopes above. Then post-war logging pushed the Japanese macaques — Macaca fuscata, the northernmost non-human primate on earth — down towards the orchards and villages of Yamanouchi-machi, where they were treated as pests. Jigokudani Yaen-koen opened in 1964 as a compromise: feed the animals in the gorge, and they would stay out of the farms. The park has operated on that principle ever since, and a well-run nagano snow monkey private tour still turns on the same logic — the monkeys are wild, unfenced, and free to leave. What visitors encounter is therefore not a zoo. Roughly 160 macaques move through a home range that extends far beyond the single artificial pool built for them in the 1960s. Keepers scatter barley at intervals; the troop arrives, or does not. Grooming lines form on the rock ledges. Juveniles slip into the water and out again. The 800 JPY conservation fee, charged per person, funds the feeding programme and the maintenance of the riverside path. The wider region gives the site its context. Shibu Onsen and Kanbayashi Onsen, the spa villages at the trailhead, have drawn bathers for centuries, and Nagano city's Zenko-ji temple — founded in the seventh century and home to what is said to be Japan's first Buddhist image — sits fifty kilometres south. Many Jigokudani Monkey Park guided day trips pair the two, moving from primate observation to a seventh-century hondo in a single day. The park's reputation abroad grew through photography, particularly a 1970 National Geographic feature, and the image has proved durable. Snow-dusted fur and steam remain the defining picture, though the troop bathes year-round. A private nagano snow monkey private tour tour condenses a long, transfer-heavy journey into one guided arc — which is why the format dominates the Nagano landmarks itinerary market.