A '''hot spring''' is a natural phenomenon where underground [[water]] is heated by [[geothermal]] energy and then flows out through the surface of the [[earth]]. Many places that have hot springs have been developed as [[spa]]s or [[resort]]s. | A '''hot spring''' is a natural phenomenon where underground [[water]] is heated by [[geothermal]] energy and then flows out through the surface of the [[earth]]. Many places that have hot springs have been developed as [[spa]]s or [[resort]]s. |