A parametric sub-bottom profiler is suitable for high resolutional profiling in the fields of sea civil engineering and hydrographic survey because of the small sized projector with the sharp directivity. We have developed a prototype profiler and tested in shallow water within 50 m deep. The projector of the profiler has the primary frequency of 88 kHz and the diameter of 28 cm. The secondary wave is 7 kHz in frequency and 10 degrees in beam width. As a result, sediment layers with 25 m thickness were observed under the bottom of 10 m depth and 15 m thick layers were also observed under the 30 m deep bottom. In addition, the parametric signal was found to be magnified when test ship crossed the wakes of other ships. It is supposed that this phenomenon is the re-radiation of the secondary wave due to the nonlinear vibration of the bubbles in water generated by cruising ships.
