The book introduces the reader to the living locators of the abysses: dolphins, whales, seals, penguins, which, using their sonar device, determine the distance to underwater objects, their size, shape, structure. The studies in question are aimed at a comprehensive study of the mechanisms of biolocation in order to improve the relevant technical means of location, one of the most important methods for studying the depths of the sea. For a wide range of readers.