A submersible fabric tub is floated in a swimming pool or other body of water, the tub having an upper floatation collar from which the flexible fabric structure of the tub is suspended. The tub has a pair of opposed bench seat portions with a deeper leg well located between them, and with enclosing end walls. A pair of access ports in an end wall connect by way of connecting hoses with an external heating or cooling water supply, by which the temperature of the water within the tub structure may be conditioned to a desired extent. The flexible floatation collar can be readily locally depressed, enabling users of the tub to readily enter or leave the tub for the surrounding body of water by swimming over the collar. The bench seat portions incorporate plastic reinforcing beams.