Editing Sonar (section)

===Underwater security===
{{main|Anti-frogman techniques#Detection}}
Sonar can be used to detect [[frogmen]] and other [[scuba diver]]s.  This can be applicable around ships or at entrances to ports.  Active sonar can also be used as a deterrent and/or disablement mechanism.  One such device is the [[Anti-frogman techniques#Cerberus|Cerberus]] system.

[[File:US Navy 030223-N-7479T-011 An AN-PQS-2A, a handheld sonar device used to aid in the search of the Toledo Bend Reservoir for debris from the Space Shuttle Columbia.jpg|thumb|upright|AN/PQS-2A handheld sonar, shown with detachable flotation collar and magnetic compass]]