Abstract: The invention relates to an apparatus for supplying divers with artificial respiratory gas mixtures with a counterlung, which can be fixed to a diver, which is hung on gimbals, which is adjusted independently of the particular floating position of the diver and which collects his exhaled gas. For the construction of a completely closed respiratory gas circuit system, it is constructed as a single-chamber container with a bottom opening and which uses the ambient water as the sealing fluid. The container is provided with a gas outlet connection arranged above the liquid level in the inner area of the container, which can be closed by means of a shutoff device controlled by the rising liquid level and which is connected by means of a waste gas hose line with the surface of the water or the inner area of a diving chamber or bell.