Onsen, or "温泉" in Chinese characters, sometimes written on maps as 湯 or ゆ, or with the symbol ♨) is a Japanese hot spring.
The heat from Onsen's come from volcanic activity underground.
All sorts of mineral are adsorbed by water as it is vapourised or "superheated" beneath the earths surface, and because of this onsen water is thought to have healing powers. Each source has a different affect on us, many of which are not completely understood - but always enjoyed.
Onsen are 'carefully' regulated by the government and must meet specifc criteria. For example, the water coming from the earth must be at least 25 degrees Celsius (77 degrees Farenheit), although the recirculating and mixing other sources is not unheard off.
We are very proud at Ryokan Issa-no-komichi BIYU-NO-YADO that we have three abundant 100% Natural sources, so there is no need to mess around with recycling hotspring water.
These days the global population is aging, and sometimes we have very young guests who 'help us to fill the onsen' - so we prefer Not to recirculate dirty water.
Onsen are important in Japanese culture, giving relief from the long twelve-hour working days.
Village ryokan onsen are open and simple which is a welcome wind-down for city folks.