Abstract: Animals produce a wide range of sounds that can travel at great distances underwater. During the presentation you will listen to the real hydrophone recordings which were made here in Hel. The paper & recordings present the results of sound imitated by grey seals. Signature sounds differ between the individuals. Seals have a well-developed sense of hearing, especially in the water. In the air, their hearing ability is greatly reduced. They have large eyes and their underwater vision is better than a human 's, but even blind mammals are healthy, because the most important sense in the water is hearing, Researchers know that seals have an acute sense of smell on land. This sense is important for mothers identifying their pups. The results of the measurements show that the sound intensity method is worth using, especially in pools , shallow water, and to identify and find the direction of a sound source.