This route is not marked. The route indicated in this post approaches Nakadake Onsen via the summit of Asahidake, and along the western wide of the Ohachidaira crater rim. This is the most exposed option for getting to Nakadake Onsen, and will likely take strong skiers around 5 hours. From the Sugatami Station at the top of the Asahidake Ropeway, follow the summer trail marked on topographical maps to the summit of Asahidake, along the prominent southern ridge of the Jigoku-dani (地獄谷) volcanic gully. Depending on the snow cover, in order to get to the top of Asahidake only on skis, you may need to stay on the snow-covered slopes to the climber’s right of the ridge, taking a more shallow traverse with a few more zig-zags. From the summit of Asahidake, take the skins off and ski down to the saddle to the east of the summit. From the saddle it is back on with the skins to make your way to the summit of Mamiya-dake (間宮岳, 2185m), where you’ll sidle around the western edge of the Ohachidaira crater rim to just before the Nakadake Bunki (中岳分岐). To access Nakadake Onsen on skis from here, you’ve got two options. Option 1 is to ski along the southern spur above the gully leading to the onsen, and drop down to the onsen just beyond the prominent rocky ‘gate’ in the onsen gully. Option 2 is a little more exciting, and involves making your way along the onsen gully and skiing through the impressive cathedral-like gully (and ‘gate’) directly to the onsen. We opted for the latter in May, and had to clamber down some rocks, as the gully was no longer fully filled with snow at that time of the year. The return to the ropeway is a traverse around the flanks of Asahidake, trying to maintain altitude as much as possible. We managed this return without skins, but it does require some side-stepping in places. From the ropeway top station it is possible to ski down the groomed ski runs or through the trees to the base of the ropeway.

If you’d prefer to just get to the campsite with minimal climbing and in the shortest time, take the return route around the flanks of Asahidake instead of going via the Asahidake summit. This will take between 2-3 hours.