Posted on May 26, 2021
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NSE
Posted on May 26, 2021
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NSE
11.5km

Distance

6.5 hours

Time

769m

Ascent

972m

Highest point

7/10
Difficulty
Snow Icon | Hokkaido Wilds
Feb-Mar

Best season

Oshamambe-dake 長万部岳 (972m) is a deceptively steep and impressive peak, despite its low height. Situated at the northern end of Oshima Peninsula in southern Hokkaido, it offers incredible views to both the Pacific Ocean and Japan Sea from the summit. The approach is long but the forest evolves as one climbs, to well-spaced white birch, with vibes of ancient times. The route is well marked to the saddle, with well-kept ski-touring specific route markers attached to trees.

We visited this route on Mar 07, 2021

Route Map

Need to know details

Location

Oshamammbe-dake sits at the northern reaches of the Oshima Peninsula in far-south Hokkaido. The winter route to the summit follows the summer trail, via an old derelict onsen, a curious bell, and a gorgeous high saddle. The route starts at the end of the snow clearing on the lonely Route 842, here, just at the turn off to the Futamata Radium Onsen 二股らぢうむ温泉.

General notes

This is a somewhat quirky ski tour route deep in the Oshima Peninsula mountains. It’s quirky in the sense that it’s one of the very few well-marked ski touring routes in Hokkaido, the approach is extremely long and gradual, the final summit approach can be surprisingly icy and dangerous, and at the end of the trip there’s a rare radium onsen at the end of it all.

The long approach is likely to put some skiers off, but this would make for a very fine overnight tent trip for the more intrepid skiers wishing to make the most of the steep (and very avalanche-prone) northeastern bowls and spurs from the summit. If shooting for an overnight trip, it would be perfectly reasonable to pull a sled all the way to the saddle beneath the summit here, or at least to the mine remains near the bell, here, for a more sheltered option.

  • Final summit push: The steep northern ridge from the upper saddle to the summit is usually hard-packed icy snow. If set on the summit, we highly recommend carrying boot crampons and an ice-axe for self-arrest.
Hut
None
Route details

Park up hard against the snow bank near the turn-off to the Futamata Onsen. Park slightly downhill from the very end of the snowclearing, to leave room for snow-clearing equipment to turn around. On skis, head northwest along the remaining snowed-in part of Route 842, past the old derelict Shin-ei Onsen. Soon you’ll pass under some high tension wires, in a large clearing with a good view of Oshamambe-dake far in the distance. From here you’ll continue to follow an old road, with plenty of ski-touring-specific route markers. Cut corners where it makes sense to do so. There will be a couple of bridges missing along the way where you’ll have to head up- or down-stream a bit to find a suitable snowbridge to cross. At around 600m, there’s a nice clearing with a bell. Give it a good ring as you gaze in wonder at the impressive east-northeastern spined face of Oshamambe-dake. From the clearing, it’s still another 1.5hrs to the summit. Just before the final summit push, there’s a saddle. You’ll want to decide early on whether to switch to crampons here or not. The ridge up to the summit is very steep and can be windswept and icy. Return the way you came. The gradual approach is mostly steep enough to zoom back in one’s up-tracks, with only occasional poling.

Route Timing
Up | 4.5hrs
Down | 2hrs

Transport

Public transport:

This route is not accessible by public transport.

By car:

Route 842 up to Futamata Onsen is conveniently accessible from the Oshamambe Expressway Interchange. There’s plenty of road-side parking on the quiet Route 842 near the turn-off to Futamata Onsen here. Park a little downhill from the turnoff to allow plenty of room for snowclearing machinery to turn around at the end of the road.

Physical maps
Official Topo Map: Obirayama (おおびらやま) – map no. NK-54-21-13-1

NOTE: The official 1/25000 topo map(s) above can be purchased for 350yen from Kinokuniya bookstore next to Sapporo Station or online (in Japanese).

Aspect
The main aspect skiers are exposed to on the descent and/or ascent is North. Other aspects that may also be encountered while following the route outlined on this page include: Southeast. Therefore, keep an eye on the weather forecast a few days ahead of your trip to monitor wind, snow, and temperature. Unfortunately there are no avalanche information services for recreational backcountry users in this immediate area (but see the JAN reports and Furano Avalanche Center for sporadic observations eslewhere in Hokkaido).

Snow and
route safety

This route is deceptively long, so requires a good early start. Note also that the trailhead is quite remote, which adds to the remoteness of the route in general. The eastern/northeastern bowls directly below the summit are a freerider’s wet dream, but are classic avalanche terrain. They’ll often be wind-loaded from the prevailing northwesters, so be very conservative. As noted above, the final approach from the saddle is steep and very often icy – carry the appropriate gear if shooting for the summit.

Oshamambe-dake Difficulty Rating

Category

Grade

Points

Strenuousness

Vertical Gain

B

35

Time ascending

B

6

Technicality

Altitude

B

6

Hazards

B

12

Navigation

B

12

Totals

71/100

GRADES range from A (very difficult) to D (easy).  More details here. Rating rubric adapted from Hokkaido Yukiyama Guidebook 北海道雪山ガイド.

Weather forecast

Windy.com weather forecast for Oshamambe-dake
Onsen nearby

Please make sure you don’t miss visiting the Futamata Radium Onsen 二股らぢうむ温泉 (location, 1100yen). It’s hands down one of the most unique onsen we’ve ever been to in Hokkaido. It has somewhat of a cult following, known for its somewhat miraculous health benefits. People with a range of health ailments will stay for weeks on end at the onsen accommodation, soaking in the pools for up to 10 hours every day. The onsen claims they’re the only onsen in the world to have radium in trace amounts in the water, safe for human soaking – see the Google-Translated full description on their website here. The outdoor pools are all mixed-gender, and there’s a surprising comradery among those staying and using the onsen. Thoroughly recommended.

Extra Resources
Yamano-Makochan's Video Report
Show Full Route Notes Close Route Notes

Route Trip Notes

Route blurb from the Hokkaido Yukiyama Guide (2015), p. 380 (translated by Hokkaido Wilds)

Oshamambe-dake, a mountain oozing with adoration and care from the local alpine club. The mountain is less than 1000m high, but it’s a precipitous and rugged peak, with a lot of snow every year. In technicality and physical endurance, it calls for plenty of experience. That said, the ski touring route is fully marked with route markers, so given good weather, it’s a very fun peak. It’s a pity the old hut part way up the route had to be demolished due to it getting too old. From the peak, you can see the Pacific Ocean and Japan Sea, plus Yotei-zan, Kariba-yama, Komagatake, and others.

We’d been going back and forward about a potential trip up Pekerebetsu-dake in the Hidaka mountains, but the past few weekends just didn’t give us the confidence-inspiring weather and snowpack conditions we were looking for for a big trip into the Hidakas.

“How about we head south?” asked Saoka. “Oshamambe-dake, for example,” she proffered.

And so it was that we committed to a two-day trip down south, staying the night at a cheap hostel near Lake Toya on the way down from Sapporo City.

We arrived at 7am at the trailhead, and met Ben there – he had driven over from Niseko that morning.

Tim, Ben and I talked shop as we took our sweet time to get ready, and by the time we got going, the others already had a solid head-start on us. We hurried to try to catch up. 

It was an interesting start to the route. The wide open landscape, a large wide river valley, had a unique feeling to it, not like other places I’ve skied into in Hokkaido. We soon picked up on the ski-tour-specific route markers as we entered the forest.

I won’t lie, it was a long way in to get to anywhere resembling decent climbing. We took turns breaking trail in the deep snow along the access road. Fifteen minute rotations to keep people fresh. There were a few bridges missing, so this kept things interesting, as we had to find suitable places to cross the streams.

The day was rapidly warming up, and the snow surface was suffering. The blue skies kept sprits high though, as did the glimpses of Oshamambe-dake’s impressive eastern face.

Navigation for the most part was made easy due to the regular large route markers. Unlike the scary-looking eastern face of Oshamambe-dake, this market route was pleasant, head up through old-growth forest, along interesting topography.

We soon found ourselves at the saddle below the summit. Here, the blistering heat from the sun was replaced by a stiff cold wind. We soon discovered the final approach to the summit would not be a walk in the park. We all switched to ski crampons and started up the ridge.

Very soon, however, it was clear that this very exposed, steep, and mildly sastrugi-like ridge wouldn’t be suitable for the whole group, with a range of members with differing experience with hard, icy, steep snow. So I veered us off to the northern slope, in hopes of finding some less wind-affected snow. This improved things a little, but not enough for Haidee’s liking. Madoka still had a slightly sprained ankle from a fall a few weeks ago, so she returned to the saddle with Haidee, where they dug in to wait out return from the summit.

Tim, Ben, Saoka and I pushed on, on a very steep, sometimes very hard surface. We did get reprieves every now and then in the form of soft snow. Saoka was having issues with her G3 ski crampons coming off at very inconvenient times, and my ski pole decided to fold in half along the way. We made it to the north-northwestern ridge heading up to the summit, and were happy to see it was, as anticipated by the contour lines, less steep than the northern ridge. The snow surface was still rock-hard though, so we made our way up very carefully. 

 

Our progress had been slow, but finally we made it to the summit. Or so we thought. As it was, we were now on a very prominent false peak, with the actual marked peak about 100m away along a flat summit ridge. Between us and the peak proper was a large wind-blown cornice. All things considered, we figured we were as atop this icy peak as much as we every would be, even if we made it to the sign, so we decided to call it good.

The views were incredible. Pacific Ocean. Japan Sea. Niseko ski resort. Kariba-yama. Komagatake. Extraordinary.

The joy of getting to the summit was somewhat dulled by the fact that we still had a sketchy descent waiting for us. Icy, rock-hard snow. I was feeling confident, but not all the party was. “I think I’ll just keep my skins on for the descent,” said one, who will remain nameless. We managed to talk them out of that option, owing that edges would be the only thing keeping them from skidding all the way to the bottom of the valley on that bullet-proof snow.

After some harrowing turns getting down the ridge, we made it onto the northern slope, and made a long traversing beeline to the saddle. We were happy to see Haidee and Madoka, who had sat out in a dugout, out of the wind. 

Time was getting on, and we were aware that we still had a long way to go to get back down to the cars. We weren’t 100% sure how easy the flat-ish approach would be. Would be we poling all the way? Would we, god forbid, have to put the skins back on?

In the end, it was a mostly rip-roaring time back down. Yes, the snow was grippy and warm. Yes, the approach road was flat-ish, but keeping to the skin track, we made good time, hardly having to pole at all.

Towards the end of the approach road, we came across ski mobile tracks, which allowed for a bit of skating here and then to speed things up even more.

Everyone was pretty happy to see the cars at the end of it all though. And even more happy to see the onsen! A fitting, relaxing end to a very worthwhile, eventful trip.

Comments | Queries | Reports

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Oshamambe-dake Difficulty Rating

Category

Grade

Points

Strenuousness

Vertical Gain

B

35

Time ascending

B

6

Technicality

Altitude

B

6

Hazards

B

12

Navigation

B

12

Totals

71/100

GRADES range from A (very difficult) to D (easy). Hazards include exposure to avalanche and fall risk. More details here. Rating rubric adapted from Hokkaido Yukiyama Guidebook 北海道雪山ガイド.