A spa cover comprising: a) a bladder section having a length and a width approximating that of a water spa; b) a plurality of elongated and generally parallel structures affixed to and substantially spanning the width of the bladder section; c) a plurality of flexible rods affixed to the bladder section and under sufficient tension to compress and create an arc over the width of the bladder section; and d) a cover supported by the flexible rods; wherein the rods and the elongated structures are spaced sufficiently to allow the bladder section and the cover to be rolled lengthwise.