An ultrasonic cleaning apparatus which is configured for transportation to an object positioned for use for in situ cleaning and a method for accomplishing the cleaning. In one embodiment, the present invention provides a substantially planar transducer array which can be employed to clean biofouling from heat exchangers or other devices that are disposed in a contaminated liquid environment. Sufficient levels of power can be generated so that the liquid medium in which the cleaning apparatus is disposed can be caused to undergo cavitation to effect the desired cleaning action. Through the use of various types of instrumentation, areas which need to be cleaned as well as the effectiveness of cleaning and the operating parameters of the apparatus can be determined. The transducers are oriented so that they radiate in alternate directions to produce bi-directional radiation and are energized by a pulsating power input.