Onsen is translated as “hot spring,” but this term can be misleading. Onsen are not always fed by a natural hot spring.

Some places heat their water with a wood fire, while others simply use a boiler. If you smell sulfur, you will know you have found the real thing. Often, different minerals will be added to the bath water to make it more beneficial. Most people come to an onsen for the atmosphere rather than their health, however.