Abstract: A method and apparatus which uses ultrasonic techniques to inspect critical pipe joints and other critical industrial areas that are normally inaccessible. A waveguide including one or more flexible fibers is embedded in concrete or whatever else embeds the piping which includes the critical area. One end of the waveguide is accessible so that an ultrasonic transducer can be used to transmit ultrasonic signals along the waveguide and receive reflected echoes to provide an ultrasonic image of the critical area. In a case where the area to be inspected is submerged, the waveguide takes the form of a flexible fiber bundle which is manipulated until its end is adjacent to the critical area. Some of the fibers in the bundle can be used to illuminate the critical area, and other fibers can transmit optical images for display on a video monitor. In an alternative embodiment, a single optical fiber waveguide is used to transmit illumination, optical signals and ultrasonic signals.