What is an onsen and what is the difference between an onsen and a sento? The onsen is a Japanese public bathhouse with natural hot spring water. The essential difference between an onsen and a sento (communal bath house) is that the water in an onsen must be volcanic spring in origin, even if reheated, whereas a sento may use ordinary heated water Do women and men bath together? There are separate facilites for men and women, although very small children of either sex up to about 8 years old can often be seen in both male and female baths. Mixed-sex bathing is a tradition that persists at onsen in the more rural areas of Japan, although these days there is usually a separate women-only bath in addition to the mixed bath. Do you have shower before you go into an onsen, what is the proper hygiene? After entering the bathing area, one should pick up one bucket and one stool and select a free set of faucets. Before sitting one may quickly rinse the stool. Some customers also use the bucket to get some water out of the bathtub to quickly rinse their genitals. Afterwards one should proceed to wash himself or herself at the faucet. One should use the towel to scrub your back, and use soap and shampoo liberally. One should try not to splash too much water on his or her neighbors. It is essential that one is clean before entering the bathtub, as in Japan people wash themselves outside of the bathtub and use the bathtub only for relaxation. When one is clean, he or she should store his or her equipment in his or her bucket and head towards the bathtub. Is it ok to wear a swimsuit as i don't know if i could be brave enough to nude up in front of others? No, it is not okay to wear swim suits in an onsen. Wearing swimsuits is explicitly forbidden at the more traditional onsen and would be considered odd at least. Try to find a place which offers private bath. There are many ryokans who offer private baths, although you may have to pay additionally, depending on the ryokan. How hot is a hot spring?   It is significantly above the ambient ground temperature (which is usually around 55-57 °F or 13-14 °C