[Access] About 1 hour by car from Kiso-Fukushima Station on the JR Chuo Line
[Website] Ontake Kogen Onsen Komorebi no Yu (Japanese)
For my hike up Mount Ontake, I had hoped to combine it with a visit to Nigorigo Onsen. However, considering the round trip from Hamamatsu would be a strenuous day trip (almost 5 hours one way to the trailhead), along with my desire to enjoy spots like the summit of Ohtaki, Kengamine, Sai-no-kawara, and Mount Mārīshiten, climbing from the Nigorigo Onsen side became unrealistic. And I had to give up that idea.
I left Hamamatsu around 1 AM and arrived at the trailhead by 6 AM. From there, I hiked from Tanohara to the summit of Ohtaki, Kengamine, Ni-no-ike, Sai-no-kawara, and over to Mount Mārīshiten, spending nearly 8 hours in the mountains. Being a 3,000-meter peak, it was cold, and I was exhausted. I was determined to find an onsen, so I searched and discovered Ontake Kogen Onsen nearby. Since it’s an active volcano, I was sure it would have great hot springs, so I hurried there by car.
I expected the area to be crowded since it seemed close to a campsite, but the building turned out to be small and cozy, with few people around.
At the entrance, there was a faucet that likely dispensed the onsen water. Noticing the brown deposits around it, my anticipation grew as I thought the onsen might be quite interesting.
Upon entering the bath, I was taken aback. The hot spring water was a deep brown, completely lacking in transparency. The mineral composition is described as carbon dioxide, iron (II), calcium, magnesium, and bicarbonate cold mineral water, with a total mineral content of 3107 mg/kg. The texture felt somewhat “gritty” against my skin, but surprisingly, it was more refreshing than I expected, given its appearance. The water was heated to a perfect temperature, and if I didn’t have to drive nearly 5 hours back to Hamamatsu, I could have stayed in that delightful onsen forever.
Although the faucet outside was marked as not for drinking, it seemed the source water was drinkable. It is said to be effective for chronic digestive diseases, diabetes, gout, and anemia.