Abstract: A wave detector for use in a swimming pool includes an electrical circuit provided with an alert member and a power source for operating the alert member. The circuit is normally open between two spaced apart electrodes which substantially eliminates all power drain from the source. When the electrodes are closed by the waves in the pool, the alert member is activated with the circuit further being provided with a normally conductive control member which changes to a nonconductive state for opening the circuit to deactivate the alert member which automatically returns to the conductive state to reset the circuit for further activation of the alert member.