The underwater vessel for one or more divers is equipped with an envelope shaped in a fluidically advantageous manner. The entire interior space of the envelope including the part accommodating the diver or divers (2) is flooded, compensating openings being provided in the envelope to make a connection between the interior space and the surrounding water. This ensures that there are no pressure differences between the outside and inside of the envelope. The envelope can be of lightweight, thin-walled design and it essentially serves the purpose of creating a shape which is as fluidically advantageous as possible and ensures movement of the diver or divers with the least possible expenditure of energy. <IMAGE>
