Mt. Iwaonupuri (Mt. Io): A ski tour day-trip at the foot of Goshiki Hot Springs

Mt. Iwaonupuri (イワオヌプリ, 1,116m – also marked as Mt. Io, 硫黄山) – the smaller sister to Niseko’s Mt. Annupuri, sits to the northwest of the bustling ski slopes of Hirafu. It is a long circular drive to get there though, so it is a great way to get away from the madding crowds. Bring a towel, because you’d be mad to miss a soak in the Goshiki Onsen, just a few meters down the road from the carpark.

Route GPS File

Mt. Iwaonupuri Ski Touring (Hokkaido, Japan)

Essential details




Highest point


Best season

Route Map

The Details

  • Route GPS log: GPX file download (goes all the way to the top of Mt. Iwaonupuri).
  • Route timing: Around one hour 10 mins from the carpark to sign-posted summit, another 10 minutes to geographical summit. 50 minutes down.
  • Topographical maps: For topographical maps, you can either print out what you want from the Geospacial Information Authority of Japan here (Mt. Iwaonupuri is in the cross-hairs), or buy the following 1:25,000 paper topo map (for 350yen) from a bookstore in Sapporo (such as Kinokuniya next to Sapporo Station).
    • Annupuri (アンヌプリ) – map no. NK-54-20-7-2
  • Snow safety: As per the Hokkaido Yukiyama Guide (p.227), the large southeast bowl and the eastern ridge is prone to avalanches in unstable conditions (see POIs on map below). Four people have been involved in avalanches in the bowl, according to the Sangaku Nadaredaizen (Snow Damage Team, 2015, p. 270).
  • Other resources: See the write-up (in Japanese) on p. 226 of the Yuki-yama Guide (ISBN: 978-4894538047).
  • Getting there and away: There are no public transport options in winter for getting to the start of the winter route. The carpark next to Goshiki Onsen is here:
  • Onsen neaby: Goshiki Onsen is highly recommended.
  • Weather forecast (Google Translated): Tenkura pinpoint
  • Date visited: Dec 25th 2016

Climb and Ski Report

This would turn out to be our second climb for the day, having previously hiked up the old Chisenupuri Ski Area earlier in the morning (report here). With that as a warm-up, we made the most of a bluebird day to explore a little bit of Mt. Iwaonupuri, behind Goshiki Onsen.

Mt. Iwaonupuri Ski Touring (Hokkaido, Japan)

The route is fairly easy, earning a ‘beginner’ rank in the Hokkaido Yuki-yama Guidebook (ISBN: 978-4894538047). It starts at the end of the snow-cleared section of Route 66, and starts off flat for a few hundred meters before cutting to the northwest just on the Kutchan Town border (marked with road signs).


Mt. Iwaonupuri Ski Touring (Hokkaido, Japan)
From there, the route follows the town border (marked on maps) along the western ridge of a large bowl on the southern slopes of the still-active volcano that is Mt. Iwaonupuri. The lower 150m or so of the ridge is a bit of a labyrinth of thin trees, but soon opens up.
Mt. Iwaonupuri Ski Touring (Hokkaido, Japan)

Mt. Iwaonupuri Ski Touring (Hokkaido, Japan)
Further up the ridge, the bowl to the east (particularly the western side), is prime avalanche terrain, so check conditions before venturing into that area.
The ridge can also be very wind-swept and icy, so take a wide berth westwards from around the 900m altitude mark towards the summer track if the going is too icy.
Mt. Iwaonupuri Ski Touring (Hokkaido, Japan)

This still being Haidee’s first time on skins in the backcountry, we opted not to go all the way to the top of Iwaonupuri, only making it to around the 1,000m mark before heading back down (our GPS trace here). Josh, with his snowboard, hiked up a little further before getting in some very nice lines with a picture-perfect Hokkaido backdrop.


Mt. Iwaonupuri Ski Touring (Hokkaido, Japan)

Mt. Iwaonupuri Ski Touring (Hokkaido, Japan)
Mt. Iwaonupuri Ski Touring (Hokkaido, Japan)

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