Abstract: Apparatus for the production of energy and method for utilizing the pressure and/or temperature conditions in deep waters, particularly in the sea, for the production of energy. Two similar tanks are provided which are adapted to contain a flowable medium which can be influenced by the outside pressure and/or the outside temperature. The physical state of the medium, particularly its state of aggregation and/or its volume, can be varied under the action of pressure and/or temperature. One of the tanks is lowered into a deep water or sea in which the pressure and/or temperature conditions are substantially different from the atmosphere outside the water, and this difference causes the medium to rise in a connecting pipe connecting the two tanks to flow into the other tank which is arranged on the water surface outside the water in which the energy of flow of the rising medium as it flows to the other tanks through the connecting pipe is utilized.