Abstract: In order to improve the buried objects search capability, there is a need to investigate new techniques that will enable the detection, localisation and classification of buried mines. Indeed, mines buried in marine sediments represent a severe threat, especially in coastal waters. Moreover, an inventory of objects buried in harbour areas is necessary to assure the security of ships. Parametric sonars are the new class of devices that allow to penetrate the sea floor. However their efficiency depends strongly on natural conditions in the sea. The dependence is of great importance in the shallow sea with considerable changes of acoustical conditions during the year. The paper contains the results of research of effectiveness of nonlinear wave generation in the Southern Baltic conditions basing on in situ measurements of the hydrological parameters.