Side Scan Sonar

Side Scan Sonar is a marine geophysical technique that is used to image or "see" the ocean floor (or lake or river bottoms). The method uses pulses of sound (sonar) shot sub-horizontally across the sea bottom from a towed transducer or towfish. The sound pulses reflect off of relief or objects that project above the bottom. The strength and travel time of reflected pulses are recorded and processed into an image or picture of the bottom. The technique is exactly analogous to taking a low-angle (as opposed to overhead) photo of the sea floor using a flashbulb and black and white film. The difference is that side scan sonar illuminates the sea floor with a pulse of sound rather than light. Since it uses sound rather than light, side scan sonar works even in murky or black water.