The book tells about the destruction of submarines at the beginning of the formation of the Northern Fleet Submarine, during the Russo-Japanese War, the First World War, the Great Patriotic War, the years of the Cold War and in the post-war period. Photos are posted and the combat path of the dead submarines is shown. Over the last half century alone, nineteen domestic submarines have been lost. In total, the Fatherland lost about a thousand submariners in disasters and accidents during this period; in six disasters, submarine crews were killed in full force along with the ship. Five domestic nuclear submarines rest at the bottom of the seas and oceans. The tragic events that claim the lives of dozens and hundreds of defenders of the Fatherland should not be forgotten and must be immortalized, as the date April 7 was immortalized - the Day of the sinking of the nuclear submarine of the Red Banner Northern Fleet K-278 (Komsomolets), which entered the hearts of all submariners and the overwhelming majority of the population of the post-Soviet space, as a day of remembrance and mourning for the crews of lost submarines. The memory of dead submarines and submariners will forever remain in people’s hearts and will be carefully preserved by submariners of new generations.