Abstract: An inflatable cushion including a watertight container adapted thereto, the container being provided with an eye for threading a carrying strap therethrough. The container includes an upper and a lower hollow part, each of which is open at the front face, and an intermediate piece whereby the container is provided with separated upper and lower cavities. The upper and lower parts are attachable directly to one another without said intermediate piece to form a cavity of about double size. The cushion is adjusted in its dimensions to the container so that it will fit into one of the separated cavities only when in a non-inflated condition. The watertightness of each one of the cavities is maintained when the other part (forming the respective other cavity) is separated from the intermediate piece.