Abstract: A method for locating leaks in liquid-transporting submerged pipelines. A sonar device directs acoustic waves along the path of a submerged pipeline and the reflected waves are detected and recorded. The location of escaping liquid is then determined from the recorded reflected acoustic waves, the differences in the reflected acoustic waves resulting from the difference in acoustic impedances between the escaping liquid and seawater. Gas and/or a liquid having a different acoustic impedance from the seawater in or under which the pipeline is located may be introduced into the pipeline to enhance the detection of the liquid being transported through and leaking from the pipeline. Also, sediments stirred up by fluids leaking from a submerged pipeline and, particularly, a buried or partially buried pipeline will cause determinable differences in the recorded reflected acoustic waves. Further, the crater excavated by the escaping fluids will be revealed by the reflected acoustic waves.