Issues of communication with divers, pressure chambers and rigid diving devices during underwater diving are considered: features of speech transmission and perception along communication paths, operation of individual communication elements, methods of improving speech quality, basic electrical and structural diagrams of communication equipment, as well as the design of its individual units, maintenance and methods of eliminating characteristic malfunctions of equipment. The book is written in the form of questions and answers and is designed for a wide range of specialists related to underwater workers, as well as students and cadets of educational institutions, designers of communications equipment and diving equipment