This publication is the most complete reference book on Soviet submarines during the Second World War, and has no analogues both in Russia and abroad. For the first time in Russian literature, not only the tactical and technical elements of wartime submarines are presented, but also the characteristics of navigational, artillery, mine-torpedo, anti-submarine and radio-technical weapons, as well as optical surveillance and communication equipment are presented. At the same time, not typical tactical and technical elements are given, but the individual characteristics of specific ships. The book lists the main events of the combat activities of submarines, lists all their torpedo attacks indicating the results, all military campaigns indicating the dates of release and return, and also indicates all the commanders of submarines during the Great Patriotic War. In addition, the book contains cases of the most severe and atypical accidents with Soviet submarines, and for the first time the issue of inter-theater maneuver by submarines, including by rail and inland waterways, is most fully covered.