A hot tub is a large tub or small pool full of heated water and used for pleasure or hydrotherapy. Some have jets for massage purposes. In contrast to a typical bathtub, a hot tub is designed to be used by more than one person at a time and is usually located outdoors. Also, the water is not changed with each use, but is kept sanitary using similar methods as swimming pool sanitation. Hot tubs are sometimes also known as spas or by the trade name Jacuzzi.
