This small guide describes a truly off the beaten tracks destination. It brings you from a very small onsen town, Numajiri Onsen, to the area where the hot water gushes out of the ground (the discharge point). There, you can bath in a mountain stream warmed by the onsen water.
: Numajiri Onsen Motoyu (沼尻温泉元湯)
: about 4 kilometers from the bottom of the ski field in Numajiri Onsen, north-east of Fukushima-ken.
: as long as there is no snow; we hiked there in late November without problem.
: good mountain shoes, a towel to dry yourself after the bath and a copy of this page with the map, as the spot is not that easy to find...
: check weather conditions and volcanic activity before hiking; be especially aware of possible rain, as the trail is potentially dangerous at one single point.
- by public transportation : Take the JR Banetsu-sai Line from Koriyama station, on the shinkansen line, to Inawashiro (41 minutes, 650 yens); from there, the bus takes 25 minutes to Numajiri Onsen;
- by car : 21 kilometers from Inawashiro-Bandaikougen IC on the Banetsu Expressway. Possibility also to drive directly from Fukushima-city.
Numajiri Onsen (沼尻温泉)
Numajiri Onsen Motoyu (沼尻温泉元湯, approximative point)
Parking lot at the top of the ski field)
At the bottom of the Numajiri ski field, a large sign indicates “Shiraito fall, 3 km” with an arrow in the direction of the small road climbing rather steeply in the forest. This road goes up to a parking lot, crossing most of the skiing area. It is possible to drive, but keep in mind that the road is not in a very good shape and has many holes; we still managed to pass with a normal car, and the road even seems quite busy. Alternatively, you can walk in 40-50 minutes to that parking lot.
There are two trails leaving toward the mountain from the parking area. The largest one, easily recognized by the presence of many stairs, is bringing the visitors in 5-10 minutes to a view point on the Shiraito waterfall (白糸の滝).
To go to the onsen, take the second smaller path, at the far end of the parking lot. If you are on the right track, you should see after a couple of meters the departure point of a small cable car used to bring material to the onsen. Just follow this path, which will bring you just above the waterfall. At that point, the slope is quite steep, and since there are no protections, caution is advised. Also if you are sensitive to vertigo, you probably will not enjoy the 2 minutes required to pass trough that point. Then the path is larger and straight forward along the mountain stream, just next to the pipe bringing the water to the onsen towns.
You will immediately notice the presence of fumes in front of you: that's where you want to go! It takes about 40 minutes from the parking lot at the top of the ski field to reach the hot spring.
The hot water does not gush out of the ground at a specific point, but rather on a fairly large surface. It is one of the most prominent hot springs in Japan, with a flow of 10'000 liters per minute! Apart of the fumes, and the presence of a lot of white suspension in the river, hikers will immediately notice two small houses – one of which is completely destroyed with only the collapsed roof remaining. And also many pipes, both in wood and in synthetic materials, which are bringing the water to several onsen towns down the valley. If you pass the houses and continue toward the stream, you will reach a small bridge. This area is an excellent spot to dip in that river!
The spring is, indeed, also directly discharging in the mountain stream, leading to a flow with very interesting – and unusual properties. The water of the river has a temperature of about 35°C, which makes soaking pleasant even in late November; its pH (acidity measurement) reaches 1.9, which means that the whole river is more acidic than pure lemon juice!
Even though, you can safely bath in such water (except if you have some open scars which then would probably be slightly burning), but keep the water away from your eyes... Last characteristics of the water are its color, milky white due to sulfur suspensions, and odor, as gaseous sulfur oxide and hydrogen sulfide (the famous rotten egg's smell) are released. If you walk upstream, you might encounter some signs warning you of high concentrations of gas; we strongly recommend not going further, as this gas is a potential thread to your health. Indeed, it is said that a fatal accident happened a couple of years ago, when mountain climbers were intoxicated after a large amount of gas was released during some volcanic activity; such evolution is always potentially dangerous in the complete absence of wind, as gas concentration can locally be very high.
In a different register, there is another concern, mostly for female hikers: absolutely no changing facility is available, which means that people who want to soak in the river have to change in the open field... or alternatively, wear some swimming costume, although it might be not recommended due to the acidity of the water.
Note that the view toward the valley is fantastic in the late afternoon...
The most precise online map is obtained from mapfan.com, using the following link : http://www.mapfan.com/index.cgi?MAP=E188.8.131.52N184.108.40.206&ZM=7
Printing and bringing that page with you is recommended.
: Many pictures and comments (in Japanese) on this trek.
: Comments (in Japanese) and some small pictures on this web site specialized on onsen.
: sean味線 blog's author read about Numajiri Onsen Motoyu on Secret Japan and decided to visit it... in late November: find out how it looks when the place is covered by snow (in English).