Abstract: A cover for the swimming pool of a multipurpose gymnasium formed of one or more sections of metal, having an undulating bend with the cavities between the bends filled with a plastic foam material to increase its strength and to act as a sound and vibration damping material. The cover is suspended from the ceiling of the gymnasium by cables and lowered into place to cover the open area of the pool. Ultraviolet lamps are also mounted on the bottom of the cover and these lamps extend partway into the pool water when the cover is in place on the pool.