Abstract: A water safety device comprises a sub-surface pressure sensing consisting of a piezo electric transducer (1) located between a sealed chamber (4) and an open chamber (2) that allows water to enter through vents (3). Changes in water pressure will result in a flexing of the piezo electric transducer providing a detectable output to the processor unit (9). The safety device also analyses surface wave motion. A ball (8) is housed within a half sphere vessel (6) that has a rough inner surface. A pimple (7) prevents the ball from remaining stationary. The half sphere vessel (6) has a lid to retain the ball within the “motion detector”. As the floating detection module rocks with the waves the ball (8) will move within the half sphere vessel (6) creating vibrations due to the rough inner surface. These vibrations are sympathy with the wave motion and are detected by the piezo electric transducer (5) located in the base of the “motion detector” within the sealed chamber (4).