A high-frequency sound source (sonar) directs a bundle narrow sound beams forward and creates an image stream (video) from the reflected echoes. The technique is analogous to that of prenatal diagnosis but is adapted to provide longer range, 1-100 m dependent on frequency, signal strength, the object's size and structure. The resolution also varies with the same variables. The technology is used for navigation of ROVs (underwater robots) and the observations of ship hulls and fixed installations, etc. The major advantage of the technique is that it works entirely independent of the level of light and visibility in the water.