The naval exercises of the crew of the submarine with tail number 812. The submarine sank into the water, lays down on the bottom, "fleeing" from the imaginary enemy. The orders of the submarine commander are transmitted. Submariners in their combat positions. Emergency alert in connection with a conditional hole in one of the submarine's compartments. The sailors close up the "holes". The diver monitors the serviceability of the submarine after the elimination of the "accident". The submarine floats to the surface.