The thermal bath is usually enriched with ozone. Ozone bubbles exert a gentle massage as they come in contact with the submerged body surface, resulting in stimulating effects and activating circulation, dilating capillaries, squeezing venous vessels, and increasing blood velocity in the periphery. Dry human skin is poorly permeable to gases and water-soluble substances, while moist skin, softened in warm water, becomes permeable by diffusion, allowing theozone dissolved in the bath water to reach the deeper layers of tissues. In addition, the large amount of ozonated air bubbles that continuously rise to the surface of the water also determine a general action on the body by inhalation of ozone at optimal concentrations, promoting absorption through the respiratory tract of the various salts in the thermal water.