Most foreigners believe that all public baths are onsen, but that’s not true. There is another type of public bath, called a “sento,” and it also offers you opportunities to take a good soak. Most sento, which are usually located in the center of a town, use tap or well water and often add artificial bathing salts or powders, various herbs, milk or even sake to the water to enhance bathing effects. Onsen are usually located on or near a volcanic mountain, contain various minerals often cost more than a sento.