Jigokudani Monkey Park

Jigokudani Monkey Park, whose name means 'Hell Valley' for the steam that hisses from its rocky ground and frozen slopes, is one of the most extraordinary wildlife encounters in Japan and the only place in the world where wild monkeys have made a habit of bathing in a hot spring. The stars are Japanese macaques — the northernmost-living monkeys on the planet — who descend from the surrounding forest to soak in a steaming pool while snow piles up on their heads. The image of a red-faced macaque with eyes closed in blissful warmth, snowflakes settling on its fur, has become one of Japan's most reproduced photographs and has appeared in countless nature documentaries.

The behavior began in the 1960s, when a young female was observed following bathing humans into an outdoor onsen. The park was established in 1964 to give the troop a pool of their own, and the monkeys have returned every winter since, passing the habit down through generations. Today around 160 macaques belong to the troop, and rangers monitor them closely; the animals are wild and free to come and go, so sightings are best but not guaranteed on warmer days.

Winter, from roughly December through March, is the prime season. On the coldest, snowiest days the monkeys stay in and around the pool for hours, grooming, squabbling over position, and dozing in the water, and this is when photographers get their best shots. In warmer months the macaques are still present in the valley — foraging, raising infants, and lounging on the rocks — but they bathe far less, since the pool's appeal is warmth.

Reaching the park is part of the adventure and deters casual crowds. From Nagano, the Nagano Electric Railway runs to Yudanaka, gateway to the Shibu and Kanbayashi hot-spring towns. From Kanbayashi Onsen, a 1.6-kilometer trail climbs through cedar forest to the park entrance, a walk of about 25 to 30 minutes that can be icy in winter — proper boots or crampons are strongly advised. The effort keeps the setting feeling wild rather than zoo-like.

Visitors are asked to keep a respectful distance, avoid eye contact, and never feed or touch the animals, which are habituated but not tame. The narrow valley, the rising steam, the surrounding snow-laden forest, and the utterly relaxed monkeys combine into a scene that feels almost staged, yet is entirely natural.

Pair a visit with a stay in nearby Shibu Onsen, whose historic bathhouses let you follow the monkeys' example in your own steaming tub. Between the wildlife, the snow, and the hot springs, Jigokudani rewards the trek into the mountains many times over, and it is accessible on a long day trip from Tokyo via the shinkansen to Nagano.