The article presents results of research on the spectral structure of the acoustic field of underwater noise generated to the water medium by selected units moving in a shallow sea. The underwater acoustic field of these units is bound with the mechanical activity of mechanisms and devices mounted in the vessel’s hull. The vibration energy originated by these mechanisms and devices is transmitted by the vessel’s construction elements to the water medium where it propagates in the form of acoustic waves in a wide frequency range. The work also presents results of identification and simulation of wave propagation included in the continuous spectrum of underwater noise.