Japanese Onsens

A Japanese onsen is a natural hot spring for bathing. Also an onsen is used to describe the bathing facilities and inns around such hot springs.

Japan is a volcanically active country, and has thousands of onsens scattered across the archipelago. Onsen by definition use naturally hot water from geothermally heated springs. Note: An onsen should be considered different from Japanese sentos, which are just indoor public bath houses where the baths are filled with heated tap water.

Major onsen resort hotels often feature a wide variety of themed spa baths and artificial waterfalls in the bathing area. Onsens come in many types and shapes, including outdoor and indoor baths. Baths may be either public run by a local city, or private run as part of a hotel, ryokan or Bed and Breakfast.

Historically, traditional onsen were located outdoors. A large number of inns have now built indoor bathing facilities as well. Onsen water is believed to have healing powers derived from its mineral content. A particular onsen may feature several different baths, each with water with a different mineral composition, at different temperatures.

The outdoor bath tubs are most often made from Japanese cypress, marble or granite, while indoor tubs may be made with tile, acrylic glass or stainless steel. Many onsens boast about their unique water and mineral compositions, plus what healing properties these may contain. Other spa services like massages are often offered.

Traditionally, men and women bathed together at the onsen and sentō but single-sex bathing has become the norm since Japan opened to the West during the Meiji period in the late 1800's. Mixed-sex (named konyoku) bathing still exists at many onsens in the rural areas of Japan, which usually provide the option of separate "women-only" baths or different hours for the two sexes. Children of either sex may be seen in both the men's and the women's baths.