An inflatable hot tub kit that includes a self-supporting tub structure that can be used on ground or used in a body of water. The kit includes a thermostat and hoses designed to connect to an external fresh water supply system. The tub structure comprises three inflatable ring sections that form the sidewalls designed to hold warm or hot water. The upper ring section is octagonal-shaped when viewed in plan view. In cross-section, the upper ring section is circular and relatively large so that when the tub structure is placed in a body of water, the water edge is approximately 8 to 10 inches below the top surface of the upper section. The middle ring section is flat in cross-section and vertically aligned under the center axis of the upper ring section. The middle ring section provides buoyancy and supports the upper ring section when used on the ground or extends into the body of water to provide buoyancy. Attached to the middle ring section is an inflatable lower ring section. Attached to the lower ring section is a flat, insulated, flexible floor panel. A suitable air inlet/outlet port and a tub-through drain are also provided.