Abstract: Swim/sporting event timer/counter. A waterproof housing has upwardly projecting digital displays and two spaced ultrasonic receivers. A swimmer wears an ultrasonic transmitter tuned to ultrasonic receivers. by measuring the time differential for the ultrasonic signals from the transmitter to reach the receivers in the housing, the position of the swimmer (i.e., in front of, directly over, or behind the housing), is determined. Laps are identified by determining when the transmitted signal changes from being received by the two receivers by an increasing time differential to being received by a decreasing time differential. Each time the swimmer passes over the housing, the numbers on the display are inverted so that the swimmer may look down into the water and see the time regardless of which direction the swimmer is traveling in the lane or other predetermined course.