Abstract: Ultrasonic depth measuring equipment comprising a sensor for emitting ultrasonic pulses in a divergent beam and for receiving the echoes of such ultrasonic pulses wherein the sensor is used in a mode such that the ultrasonic pulses are emitted upwardly through a liquid so as to be reflected from a reflecting surface, the echo being received by the sensor, the sensor being coupled to a microprocessor which is adapted to average the time taken between emissions of the pulses and the echo of the pulses being received by the sensor, and from these readings, an accurate measure of the distance between the sensor and the reflecting surface can be made.