Abstract: This paper presents the results of old and new techniques for the investigations of underwater acoustic fields radiated by different objects. In the Navy Test and Evaluation Ranges (NTER), we monitor the ship radiated underwater noise, pressure and other signatures. They are of major importance to sea mines, surface ships and submarines. The NTERs contain an accurate measurement system consisting of a bottom-mounted hydrophone array, which is used for different running vessels. We also have a special laboratory ship and a transportable multi- sensor module, which is the most recent Polish Naval Academy product. Nowadays, the problem of protecting the civilian and military harbor facilities is becoming more and more important. There is always a threat to the ports from submarines and terrorists who dive under the water.