Soranuma-dake (空沼岳) is a peak sitting between the hot springs at Jozankei Onsen (定山渓) and the lake Shikotsu-ko (支笏湖). As this area gets a huge amount of snow in the winter, there are a number of marshes that dot Soranuma-dake's slopes, namely Bankei-numa (万計沼), Mamisu-numa (真簾沼), and the eponymous Sora-numa (空沼). The etymology of the mountain's name is unclear, but it may come from one of two sources: 1) from the old name for the nearby river Izari-gawa (漁川), which the Ainu called raruma-nai (as in (so)raruma, which would have drifted to 'soranuma' over the years), or 2) from a dried-up stream on the mountainside, which would have been called 'Kara-numa' (空沼, lit. 'empty marsh’)—this uses the same Japanese characters as 'Sora-numa' would, and over time the reading may have changed over. At Bankei-numa, there are two huts: Bankei-sansou (万計山荘) and Soranuma-koya (空沼小屋)—the second one id privately run by one of the universities and is not open to the public. You can also make the traverse from Soranuma-dake to Sapporo-dake if you're in the mood for a longer walk.

   You'll find the trailhead at the end of a forest road which follows the Bankei-sawa (万計沢) stream. You'll cross a bridge and climb up into a mixed forest of evergreens and broadleaves; but it's the huge Ezo spruce around here that will really catch your eye. With a forest like this it's little wonder that Sapporo is known for its sprawling nature.

From the right bank of the stream you'll shortly cross to the left bank. A little ways after this, you'll leave the side of the stream for a bit; when you meet back up with it you'll have arrived at the small pond called Bankei-numa. In the trees by the shore of the pond lie big Bankei-sansou lodge and the smaller Soranuma-koya hut. If you can spare the time, taking a couple of days to hike the mountain and staying overnight at Bankei-sansou is a lovely way to spend your time.

A little ways above Bankei-numa you'll find the comparatively larger pond called Mamisu-numa. After wandering along the banks of the sprawling pond, the trail will head up a steep slope. You'll emerge on a ridgeline looking down onto the tops of trees. On this ridge you'll run into the junction with the trail from Sapporo-dake (札幌岳) before shortly thereafter reaching the summit of Soranuma-dake. Please note that this is the summer route. It is extremely hazardous to attempt this route in winter as there are avalanche areas and terrain traps. The winter route moves further to the west of the ridge to a slight saddle.

   Though it doesn't have much of the feel of being a major summit, the view from the top is outstanding. In particular, the mountains around Shikotsu-ko, especially Eniwa-dake (恵庭岳), are spectacular to see. Which is not to mention the hills around Jozankei or the massive cone of Yotei-zan (羊蹄山), Hokkaido's Mt. Fuji, in the distance. At times you may even see the head of a chipmunk or two poking out of the surrounding foliage.

If you were to continue along the ridge from the summit, you'd soon see the pond called Sora-numa as well; but there is no trail down that way. Your trip down will follow the same trail you came up.

Difficulty-6/10