Rinse off before going in
Depending on the facility you visit, you must either rinse off with tap water or scrub down with soap and tap water before entering the thermal bath. Bring your own soap, shampoo and towel just in case.
Take it all off
Most onsen do not allow swim suits. At these spas, there are separate baths for men and women. You can use a towel to cover up when outside of the spring water – just be sure not to let that towel fall into the bath, since the goal is the keep the water as clean as possible.
Check beforehand about an onsen’s “tattoo policy”
According to the site OnsenJapan, tattoos have traditionally signified gang or organized crime ties. While it may be discriminatory, some onsen are still not open to people with tattoos.
Do not take pictures
Many onsen do not allow photography. If you wish to photograph the surrounding scenery, ask the resort staff before taking any chances.
Drink water not booze
Drink bottled water to stay hydrated. Alcoholic beverages are not recommended as prolonged exposure to hot water can be dangerous if you are intoxicated.