What is an onsen?
Onsen are the hot spring baths of Japan — fed from the thermal springs of the volcanically active archipelago and for centuries the centre of a bathing culture of its own. An onsen is more than a warm pool: it is quiet, ritualised bathing, often under the open sky (then called “rotenburo”), with a view of a garden, a forest or mountains. Classic onsen places such as Hakone or Beppu have developed whole spa towns with traditional guest houses (ryokan) around their springs.
The rules of the bath
Japanese etiquette clearly distinguishes the onsen from the European pool: you wash beforehand, thoroughly, seated at the washing places — the pool itself serves exclusively for bathing, not for cleaning. You bathe without swimwear, speak quietly or not at all, and the small towel stays out of the water. Whoever has internalised this choreography once understands why the onsen bath counts as meditation in water.
Effect and water temperature
Onsen water is genuine thermal water with a mineralisation that depends on the spring — the pools usually lie at around 38 to 42 °C, noticeably warmer than Central European thermal baths. The effect corresponds to classic balneology: warmth for musculature and circulation, minerals for skin and regeneration — plus the mental component of quiet, contemplative bathing that makes the format so unmistakable.
Onsen in Europe
The onsen idea has arrived in the ambitious hotel spas of Europe — as a hot outdoor pool in ritual form, deliberately run in silence and framed in Japanese architecture. The HUBERTUS Mountain Refugio in the Allgäu, for instance, runs a 38 °C onsen pool on the rooftop of its Mountain Spring Spa. The original remains worth the journey: Japan's onsen towns belong to the great bathing-culture destinations of the world.
