A method is disclosed for operating an underwater vehicle. According to the method, the pressure difference between a container which can be filled with water and/or gas, especially air, in order to alter the weight of the vehicle and the water pressure outside the vehicle, is regulated to a predeterminable set value. A suitable device for carrying out this method, includes a circuit for regulating pressure difference between the pressure inside the container an the water pressure outside the vehicle to a predeterminable set value.