Young Brunette Girl With A Fringe Posing In The Bathtub

Hot tubs are common heated pools used for relaxation and sometimes for therapy. The "hippie" era (1950–1970) popularized them in America in songs and movies.
Whirlpool tubs
Whirlpool tubs first became popular in America during the 1960s and 70s. A spa or hot tub is also called a "jacuzzi" since the word became a generic after plumbing component manufacturer Jacuzzi introduced the "Spa Whirlpool" in 1968. Air bubbles may be introduced into the nozzles via an air-bleed venturi pump.