Onsen is a part of Japanese tradition. I myself became familiar with onsen during my three and a half years of stay in Japan between 2008 – 2011. The word ‘onsen’ is of Japanese origin which means ‘hot spring’. Our modern day’s hot spring SPA might be considered just an improved version of Japanese old fashioned onsen. Japan is a mountainous and volcanic country and hot springs are literally everywhere in Japan and for hundreds of years, Japanese people have been enjoying them mainly for health benefits and social interactions. Indeed, bathing at an onsen is a great way of embracing Japanese tradition!

Onsens are waters heated by geothermal energy and Japan is reputed to have more than 2,500 onsens throughout the country. Most of them are located on the surface, while others are reached by tapping subterranean sources more than 1,000 meters underground. Hot spring temperatures vary widely, from nearly 100 °C (212 °F) to as cool as 20 °C (68 °F). The one that I visited in Kusatsu, one of the famous onsen resorts in Japan, the temp was around 40 °C and it was nearly impossible for us to take bath probably because we were not used to it. Kusatsu Onsen in Gunma and Hakone Onsen in Kanagawa are very popular for relaxation and sightseeing among Japanese and overseas visitors as well.

Japan’s hot springs are often found in natural settings, among mountains, along the seashore or in narrow valleys, which add appeal to the bathing experience. There are 11 different categories of hot springs in Japan, which are classified according to their mineral composition. The most widespread is the sulfur hot spring, which can be recognized by its distinctive odor. Sulfur hot springs are common in mountain regions and can be considered the typical type of hot spring in Japan. You might be surprised to know that hot spring waters in Japan come in many different colors such as black, white, green, red, or brown. The dark color, which always surprises at first glance, comes from organic plant material.

Soaking in hot spring need not be solely reserved for a relaxing vacation, rather these mineral-rich baths offer a wealth of natural health benefits you may not know about. The healing powers of hot springs have been used for thousands of years and are widely accepted in Europe as natural treatment options for various ailments. Perhaps you have heard about ‘Balneotherapy’, which means treatment of disease by bathing, usually practiced at SPAs. It is part of the traditional medicine of many cultures and originated in hot springs, cold water springs, or other sources of such water.

Repeated hot springs bathing (especially over a 3-to-4-week period) can help normalize the functions of the endocrine glands as well as the functioning of the body's autonomic nervous system. Trace amounts of minerals such as sulfur, calcium, magnesium, and lithium are absorbed by the body and provide healing effects to various organs and systems. These healing effects can include boosting immunity as well as physical and mental relaxation.

Mineral springs contain high amounts of electrolytes, which can help promote feelings of physical and psychological wellbeing. The direct application of mineralized thermal waters (especially- those containing sulfur) can have a therapeutic effect on diseases of the skin, including psoriasis, dermatitis, and fungal infections. Some mineral waters are also used to help the healing of wounds and other skin injuries. When you bathe in a hot spring, your skin soaks in these minerals and your hydrostatic pressure rises. As this process continues, circulation and oxygen flow increases – in a similar way when you exercise. An oxygenated circulatory system is beneficial in keeping not only your heart but your body's other vital organs and tissues, healthy and strong. When you soak in warm water, your body temperature rises, then quickly cools down when your bath is complete. This body-cooling process can help you relax and fall into a deeper sleep. If you suffer from chronic muscle pain, arthritis or even fibromyalgia, soaking in a pool of hot-spring water can effectively improve pain. One study shows that hot mineral baths may aid in relieving pain and fibromyalgia fatigue.

Bathing in hot springs gradually increases the temperature of the body, thus can kill harmful germs. Thermal bathing increases hydrostatic pressure on the body, thus increasing blood circulation and cell oxygenation. The increase in blood flow also helps dissolve and eliminate toxins from the body. Hot springs bathing increases the flow of oxygen-rich blood throughout the body, bringing improved nourishment to vital organs and tissues. Bathing in thermal water increases metabolism, including stimulating the secretions of the intestinal tract and the liver, aiding digestion.

In the United States and all over the world, there are thousands of hot springs we may explore to have a thrilling experience of health benefits! If we have a chance to visit such a place, let us give it a try!