Sidescan Sonar

Sidescan sonar is used to provide high-resolution images of the water bottom, and is commonly used in marine archaeology and for creating maps.


A sidescan sonar system directs sound waves from a transducer suspended beneath the boat in a fan shape towards the water bottom. Reflections are recorded to provide an image of the water bottom to the left and right of the boat’s path. Frequencies range from about 100 to 500 kHz. Sidescan can be used to provide full bottom coverage maps of harbours at sub-meter resolution.

Figure 1. Sidescan sonar survey over a sunken barge. Note the shadow to the left of the image that can be used to calculate height of the barge above seafloor.