A method of identifying and locating an acoustic reflector is described by interrogating underwater objects with a sonar and deploying one or more of the steps of • a. identifying objects that apparently reflect the acoustic interrogation with a double echo, measuring the separation of the two echoes and comparing those measurements with anticipated measurements for underwater acoustic reflectors that may be present in the search area, and accepting or rejecting the reflected acoustic wave as potentially including the echo from the front of such an acoustic reflector and the echo from the shell at the rear of the reflector; • b. measuring the target strength of the echoes in a double echo received from an object and rejecting the object as one of interest if the target strength in the first echo of a double echo exceeds that of the second echo; • c. measuring the total target strength of an echo from an object, the object being rejected as being a potential underwater acoustic reflector of interest if the target strength is less than a predetermined minimum; • d. measuring the acoustic width of an object and comparing that with the acoustic width of known acoustic reflectors, the object being rejected as being potentially an underwater acoustic reflector of interest if the acoustic width is not that of a known underwater acoustic reflector; • e. measuring the frequency response of an object, the object being accepted or rejected as being potentially an acoustic reflector of interest if the frequency response corresponds to the known frequency response of such an underwater reflector; and • f. measuring the phase response of an object, the object being accepted or rejected as potentially an underwater acoustic reflector of interest if the phase response corresponds to the known phase response of such an underwater acoustic reflector. The target is being rejected as being an acoustic reflector of interest if the measured characteristics do not match the known characteristics of a reflector of interest.