Ontake-san (御嶽山, 3,067 m) is Japan's second-highest volcano after Fuji, straddling the Nagano–Gifu border, and one of the most sacred mountains in the country. For centuries it has been the focus of the Ontake-kō (御嶽講) mountain-worship movement, whose white-clad pilgrims still climb each summer. The mountain also carries a recent tragedy: the September 27, 2014 phreatic eruption killed 58 people near the summit (with 5 still missing), the deadliest volcanic disaster in postwar Japan. Ontake remains an active, JMA-monitored volcano, and access to its main summit depends on the current alert level.
Why Fukada Chose Ontake-san
Ontake-san appears in Kyuya Fukada's Nihon Hyakumeizan. The book is ordered roughly north to south across the hundred mountains — Ontake sits between Norikura-dake and Utsukushigahara — and is not a ranking of quality or difficulty. Fukada was drawn to the mountain's immense scale and its deep spiritual significance: a volcano so revered that it gathered mountain-worship groups from across Japan, with a broad summit massif and wide panoramas over the Central and Northern Alps.
The Mountain
| Attribute | Detail |
|---|---|
| Elevation | 3,067 m (10,062 ft) — Japan's 2nd-highest volcano after Fuji |
| Prefectures | Nagano / Gifu |
| Main summit | Kengamine (剣ヶ峰) |
| Volcano status | Active; JMA-monitored. 2014 phreatic eruption (58 killed, 5 missing) |
| Religious tradition | Ontake-kō pilgrimage, popularized in the late 18th century |
| Book order (Hyakumeizan) | Included (book order is roughly north-to-south, not a rank) |
| Typical season | July – October |
The summit area holds a chain of five crater lakes, named Ichi-no-ike through Go-no-ike (一ノ池–五ノ池). Ni-no-ike (二ノ池), near the main summit, is the highest lake in Japan. San-no-ike (三ノ池), on the Gifu side, is a famously cobalt-blue crater lake; in late spring its snowmelt forms a ring pattern locally called the "Dragon Eye" (ドラゴンアイ).
The Routes
Ontake has trailheads on both the Nagano side (two routes) and the Gifu side (one route). Always confirm the current JMA alert level and the prefectural route-status notices, as open sections change year to year.
Otaki route — Tanohara (Nagano side)
Grade: Moderate–Challenging
The Otaki-guchi (王滝口) route starts from the Tanohara trailhead (田の原) in Otaki Village, Nagano — not on the Gifu side. Tanohara sits at roughly 2,180 m and is the shortest approach to the Kengamine main summit, climbing about 880–900 m to the 3,067 m top. The trail is lined with torii gates and religious statues, giving it a continuous pilgrimage atmosphere. As of July 5, 2025, the route reopened all the way to Kengamine, along with the Otaki-summit → Ni-no-ike traverse → Kurosawa junction connector.
Kurosawa route (Nagano side)
Grade: Moderate–Challenging
The Kurosawa-guchi (黒沢口) route is the other Nagano-side approach, historically the path opened for "light purification" pilgrim ascents. It passes the Nyonindō hut and links toward the Ni-no-ike area and the summit ridge.
Kosaka route — Nigorigo Onsen (Gifu side)
Grade: Moderate–Challenging
The Gifu-side approach is the Kosaka-guchi (小坂口) route, starting from Nigorigo Onsen (濁河温泉). It runs about 4.2 km and roughly 3 hours 30 minutes to the Hida summit (飛騨頂上), where the Go-no-ike-goya hut stands. This side passes San-no-ike, the cobalt-blue crater lake.
Getting There
To the Otaki / Tanohara trailhead (Nagano side): From the JR Chuo Line at Kiso-Fukushima Station, the Ontake Kotsu bus runs to Tanohara in about 1 hour 15 minutes. Service runs daily from mid-July to late August, then on weekends and holidays through mid-October, with three departures a day. The Tanohara parking lot is free and has about 210 spaces. By car, approach via the Chuo Expressway to Kiso-Fukushima, then up to Tanohara.
To the Gifu side: The Kosaka route begins at Nigorigo Onsen, reached by road from the Hida / Gero area; check seasonal access before relying on it.
Mountain Huts
Several staffed huts serve the routes. Confirm operating dates each season, as opening depends on volcanic restrictions.
Nagano side (Otaki / Kurosawa): Tanohara-sansō (田の原山荘), Otaki-chōjō-sansō (王滝頂上山荘), Ishimuro-sansō (石室山荘), Ni-no-ike Hütte / Ni-no-ike-sansō (二の池ヒュッテ／二ノ池山荘), and Nyonindō (女人堂).
Gifu side (Hida summit): Go-no-ike-goya (五の池小屋).
Flora and Wildlife
Japanese rock ptarmigan (ライチョウ): Ontake supports a population of rock ptarmigan, confirmed by prefectural and ministry survey programs. They are most associated with the northern part of the massif around Mamako-dake (継子岳). Move quietly and keep your distance if you encounter them.
Bears: Ontake lies on Honshu, where the resident bear is the Asiatic black bear (Tsukinowaguma). Make noise on forested approaches and carry a bear bell; bear spray is not the standard expectation here as it is for Hokkaido's brown bears.
Crater lakes: The summit area's lakes — especially Ni-no-ike (Japan's highest) and the cobalt-blue San-no-ike — are among the most striking volcanic-lake landscapes in the Japan Alps.
Volcanic terrain: The upper mountain shows fumarolic ground, sulphur deposits, and bare volcanic rock, distinct from the non-volcanic Alps on either side.
Seasonal Guide
Early July: Season opens; snow lingers on the upper approaches.
August: Peak season, including the O-bon period in mid-August when Ontake-kō pilgrimage groups make their annual ascents. Busiest and warmest stretch.
September: Often the clearest views; crowds thin out.
October: Season winds down, with first snow on the upper mountain by late October.
Practical Tips for Foreign Visitors
Volcanic safety comes first. Always check the JMA volcanic alert level before climbing, and read the current-year route-status notice from Nagano or Gifu Prefecture — open sections vary. Carry a cloth to cover nose and mouth, and note the huts as potential shelter; in 2014, sheltering in huts saved lives.
The 2014 eruption. The phreatic explosion on September 27, 2014 struck at 11:52 AM during the busy autumn hiking season, with the alert level at 1 and no seismic warning, killing 58 people (5 still missing). It is the worst volcanic disaster in postwar Japan and reshaped how active volcanoes are climbed here.
Respect the pilgrimage tradition. The popular Ontake-kō pilgrimage was established in the late 18th century: the ascetic Kakumei opened the Kurosawa route and a "light purification" ascent in 1784–1785, and Fukan opened the Otaki route around 1792. White-clad pilgrims still climb the trails lined with torii and statues; behave respectfully around them.
Frequently Asked Questions
Can Ontake-san be climbed as a day hike?
Yes. The Otaki route from the Tanohara trailhead (roughly 2,180 m) is the shortest approach to the Kengamine main summit, climbing about 880–900 m to the 3,067 m top, which makes a day ascent practical. As of July 5, 2025 this route had reopened all the way to Kengamine. Several staffed huts along the routes also allow an overnight stay if you prefer to break up the climb.
Can I reach Ontake-san without a car?
Yes, on the Nagano side. From the JR Chuo Line at Kiso-Fukushima Station, the Ontake Kotsu bus runs to the Tanohara trailhead in about 1 hour 15 minutes, with three departures a day — daily from mid-July to late August, then weekends and holidays through mid-October. The Gifu-side Kosaka route at Nigorigo Onsen is reached by road from the Hida / Gero area, so confirm seasonal access before relying on it.
Is the main summit open, and what should I check first?
Access to the main summit depends on the current volcanic alert level. As of July 5, 2025 the Otaki route reopened all the way to the 3,067 m Kengamine main summit, but this can change. Ontake is an active, JMA-monitored volcano, so always check the Japan Meteorological Agency (JMA) volcanic alert level and the current-year route-status notice from Nagano or Gifu Prefecture before every visit, and carry a cloth to cover nose and mouth.
When is the best time to climb, and when does the snow clear?
The typical season is July to October. The upper mountain holds snow into early July; August is the peak and warmest stretch (including the mid-August O-bon pilgrimage period); September often gives the clearest views with thinner crowds; and first snow returns to the upper mountain by late October.
What bears live on Ontake-san and what should I do?
Ontake is on Honshu, where the resident bear is the Asiatic black bear (Tsukinowaguma). Make noise on forested approaches and carry a bear bell. Bear spray is not the standard expectation here as it is for Hokkaido's brown bears.
This guide is part of the Japan's 100 Famous Mountains: Complete Hyakumeizan Guide series.
