↘ Tokachidake — Sandan-yama

⚠️ [Read first — active volcano, Alert Level 2] Tokachidake is an active volcano and has been at JMA Volcanic Alert Level 2 (crater-vicinity restriction) since June 2026. A ~1.5 km no-entry radius surrounds the most active 62-2 crater, and the summit of Tokachidake itself lies inside that no-go zone. Sandan-yama (1,748 m) is one of the very few objectives that sits just outside the restriction — its summit is about 1.6 km from the 62-2 crater, right on the edge of the line. That means straying even a little toward the craters can put you inside the restricted zone. Even on this route, always check the live JMA volcano bulletin before you go, and never move toward the craters.

[Route overview] Sandan-yama climbs the northwest flank (aspect NW) from Tokachidake Onsen / Hakuginso (~1,280 m; trailhead 142.6416E / 43.4314N), gaining about 733 m of vertical over a ~6.2 km round trip — an entry-to-intermediate tour of the Tokachi range. The high trailhead keeps the climb modest, but the ridge and upper slopes are wind-exposed, with short pitches reaching about 42° (that max-slope figure reflects brief steep sections, not the angle of the skin line as a whole).

[Terrain and the climb] True to its name ("three-tier mountain"), the route steps up through a series of benches; above the trees it opens into wind-scoured, featureless flats. In the cold Central-Hokkaido snowpack the surface is commonly a mix of wind deposit, crust and hard slab, and the NW face — which takes the Siberian NW wind head-on — is especially prone to wind slab. The Tokachi range tends to carry a persistent weak layer, so treat this as unambiguous avalanche terrain that demands your own stability assessment.

[The gas crater is close — do not enter] Sandan-yama itself is outside the restriction, but the Ansei crater (安政火口), which vents volcanic gas, is a short distance away. Volcanic gas (SO2 / H2S) pools in hollows and crater floors and can reach dangerous concentrations downwind even when you cannot smell it. Never enter the Ansei crater or any crater terrain. Be aware too that geothermal hot ground can melt thin snow into hidden steam voids — a real break-through hazard.

[Critical descent caution — aspect and whiteout] Tokachidake is an isolated volcanic cone, and high up, near-identical, featureless slopes fall away on every side. In flat light (overcast or fog that erases all shadow and texture) or in ground blizzard it is easy to confuse the NW face you climbed with an adjacent one and ski onto the wrong aspect — in the worst case, into the restricted zone or toward the craters. This is a classic, recurring error on cones like this. Confirm your descent bearing with GPS and compass, never edge from the restriction line toward the craters, and do not push for the top in poor visibility.

This is not a recommendation. It is a description of terrain that is avalanche terrain end to end and sits on the very edge of an active-volcano restriction — a double risk. Check both the JAN Central Hokkaido bulletin and the JMA volcano bulletin, and own every decision and its outcome yourself.

[Trailhead & parking] The route starts at Tokachidake Onsen / Hakuginso (~1,280 m; 142.6416E / 43.4314N). The road is plowed in winter and you can use the Hakuginso / Tokachidake Onsen parking, though capacity and plowing vary with the weather — check ahead. Starting at 1,280 m, you are already near treeline at the trailhead.

[Getting there] Approach via the prefectural road up to Tokachidake Onsen from Kamifurano. Expect snow and ice on the road in winter — a 4WD vehicle with winter tyres or equivalent is appropriate. Public transport is limited and infrequent, so a private car or an arranged tour is the practical option.

[Check the restriction (most important)] Before you go, always confirm the volcanic alert level and restricted area on the JMA Tokachidake volcano bulletin. Sandan-yama currently sits just outside the no-go zone, but any change in the alert level or the restricted radius changes everything. Pair this with the JAN Central Hokkaido bulletin for avalanche conditions.

[After] There are onsen nearby, including Hakuginso and Fukiage Onsen. Hours and winter closures vary by venue, so confirm locally.