Abstract: A floating digital display thermometer for a hot tub, spa or swimming pool, having a motion-sensitive switch responsive to wave action or intentional manipulation. The components are arranged within a watertight housing to ensure that a digital display always remains up to ensure easy viewing. Circuitry is provided for converting temperature readings to a digital display, and for indicating other functions such as time and date, and for providing alarm and music capabilities. Manually-activated membrane switches may be provided to activate various functions of the device. Furthermore, the thermometer is also capable of measuring and displaying the PH and the oxidation reduction potential of the liquid in the spa or swimming pool.