Hakone Onsen has a long history, and in particular, Yumoto Onsen is said to have been opened in the Nara Period, and there are also records of military commanders bathing there in the Kamakura period. From the late Edo Period, it became officially recognized as an onsen (hot spring) destination, and from the Meiji Period, with the advancement of hot spring excavation technology, development progressed and currently, there are 20 hot springs in Hakone. These hot springs have a wide variety of hot spring qualities and because of this, they are known as the “department store of hot springs”. The hot springs can be broadly classified into 4 groups, simple hot springs (hot springs gushing from old strata before the formation of Hakone volcano), chloride springs (hot springs that gush from within the caldera of Hakone volcano and were formed by an eruption 66,000 years ago and were buried underground), sulfate springs (hot springs gushing from the crater remains of Hakone volcano, buried underground from approximately 80,000 to 40,000 years ago), and sulfur springs (hot springs containing volcanic steam that erupt from Owakudani). Through detailed studies of each hot spring, a world-renowned model of hot spring formation has been constructed, which is now being reexamined based on the latest history of volcanic formations. Table 1 summarizes the main spring qualities and effective treatment for each hot spring. Please refer to Figure 1 for locations.
| Hot Spring | Main Spring Qualities | Effective Treatment |
|---|---|---|
| Hakoneyumoto Onsen | Alkaline simple hot spring, sodium-chloride spring, Sodium/Calcium – Chloride/Sulfate Spring | Autonomic nervous instability, insomnia, etc. |
| Tounosawa Onsen | Alkaline simple hot spring | Autonomic nervous instability, insomnia, etc. |
| Ohiradai Onsen | Alkaline simple hot spring, Sodium-chloride spring | Autonomic nervous instability, insomnia, etc. |
| Dogashima Onsen | Simple hot spring, Sodium-chloride spring | Autonomic nervous instability, insomnia, etc. |
| Miyanoshita Onsen | Sodium-chloride spring | Cuts, peripheral circulation disorders, sensitivity to cold, etc. |
| Sokokura Onsen | Sodium-chloride spring | Cuts, peripheral circulation disorders, sensitivity to cold, etc. |
| Kiga Onsen | Simple hot spring, Sodium-chloride spring | Cuts, peripheral circulation disorders, sensitivity to cold, etc. |
| Kowakudani Onsen | Simple hot spring, sodium-chloride spring, Sodium – chloride, sulfate, hydrogen carbonate spring | Cuts, peripheral circulation disorders, sensitivity to cold, etc. |
| Ninotaira Onsen | Simple hot spring, Sodium-chloride spring | Cuts, peripheral circulation disorders, sensitivity to cold, etc. |
| Goura Onsen | Simple hot spring, Sodium-chloride spring | Cuts, peripheral circulation disorders, sensitivity to cold, etc. |
| Miyagino Onsen | Sodium-chloride spring, Sodium/Calcium – Chloride/Sulfate Spring | Cuts, peripheral circulation disorders, sensitivity to cold, etc. |
| Ashinoyu Onsen | Simple sulfur spring, sulfur-containing /sodium/magnesium-sulfate/hydrogen carbonate spring | Atopic dermatitis, chronic eczema, etc. |
| Yunohanazawa Onsen | Simple sulfur spring | Atopic dermatitis, chronic eczema, etc. |
| Souunzan Onsen | Simple hot spring | Atopic dermatitis, chronic eczema, etc. |
| Owakudani Onsen | Acidic – Calcium/Magnesium – Sulfate/chloride spring | Atopic dermatitis, diabetes, etc. |
| Ubako Onsen | Simple hot spring, calcium/magnesium/sodium-bicarbonate/sulfate spring | Cuts, peripheral circulation disorders, sensitivity to cold, etc. |
| Sengokuhara Onsen | Simple hot spring, calcium-sulfate spring | Cuts, peripheral circulation disorders, sensitivity to cold, etc. |
| Kojiri Onsen | Sodium, calcium, magnesium – sulfate, hydrogen carbonate spring | Cuts, peripheral circulation disorders, sensitivity to cold, etc. |
| Takogawa Onsen | Calcium/sodium-chloride/sulfate spring | Cuts, peripheral circulation disorders, sensitivity to cold, etc. |
| Ashinoko Onsen | Simple hot spring | Autonomic nervous instability, insomnia, etc. |
“*Note: Each hot spring location also has hot springs with spring qualities other than those listed in the Main Spring Qualities.
Effective Treatments may vary depending on the quality of the hot springs even at the same hot spring.”