onsens

Onsen refers to natural hot springs in Japan and the towns built around them. The water is heated by geothermal activity and often contains minerals dissolved from surrounding rocks. Japan has thousands of onsen springs, concentrated in volcanic regions across Honshu, Hokkaido, Kyushu and Shikoku, as well as in rural mountain areas. An onsen typically includes the spring itself and the facilities that use it, such as bathhouses, public baths, and traditional inns known as ryokan.

Mineral composition varies by source. Common types include sulfur onsen with a distinctive acrid smell, iron-rich waters that turn yellowish, carbonate springs, and saline springs. The mineral content is traditionally believed to have therapeutic effects, including skin and circulatory benefits, though scientific evidence is mixed. Onsen water is often clear, but it can be cloudy or colored depending on minerals.

Etiquette and access: visitors typically wash and rinse the body before entering the bath, do not wear swimsuits, and towels are kept outside or placed on the head. Bathing is usually performed nude in gender-segregated blocks, although some facilities offer private baths or days with mixed bathing. Tattoos are commonly restricted or require covering in many traditional onsen, though policies are changing in some places.

Cultural and economic role: onsens are a cornerstone of Japanese tourism and regional culture, often tied to ryokan lodging, kaiseki cuisine, and scenic settings. They draw domestic and international visitors seeking relaxation, nature, and tradition. Environmental stewardship is important to protect spring sources from overuse, extraction limits, and temperature changes.