Abstract: A container made of deformable sheet material comprises two panels generally facing one another and having perimetric edge zones bonded fluidtight to one another. In at least one of the panels deformation-enhancing corrugations are provided whereby the container is expandable from a flat state into an inflated state. The container may have a filler unit which comprises a tubular nipple attached to the container; a closure cap received on an outer end of the tubular nipple; a collar attached to the inner circumferential surface of the tubular nipple at an end thereof oriented towards the container; a breakable closure disc extending across the flow passage and having a circumferential edge zone in engagement with the collar; and an inner ring threadedly engaging the inner circumferential surface of the tubular nipple and pressing the breakable closure disc against the collar.