Abstract: A solar heating device for swimming pools comprising an inflatable raft having a thermally reflective bottom surface and a thermally transparent top surface, and means for elevating at least a fraction of said reflective surface above the swimming pool surface during periods of diminished solar radiation to reduce heat loss from the water. One raft is generally small enough to be easily handled and a plurality of rafts may be required to cover a substantial part of the water surface. The number of rafts required is variable and provides a measure of flexibility to the rate of heating, i.e., by providing more rafts in spring and fall and perhaps none in mid-summer.