Abstract: The present invention concerns those elements that, by means of valves, allow the balance of forces acting upon the walls of a hermetic container during its sinking in a liquid, thus preventing the stress produced due to the effect from an increased volume of liquid applied on the external face of the container. It also prevents spillage of the content into the surrounding environment through the said elements and is provided with the means to equally balance the forces cited during eventual re-floatation of the aforementioned container.