Sunscreen should be reapplied after sweating or swimming. Realize that even if you are not hot, the sun can still damage your skin. Skin needs to be protected year around, even on cloudy days. Pack the sunscreen. Sand, water and snow can reflect and intensify the sun's rays.
Radiation is more intense the higher the altitude and the closer to the equator.
Wear a hat to shade your face and ears. Be careful with babies. If you have additional questions about sun and skin care, consult a dermatologist or your physician. Center on Aging, University of Kansas Medical Center, July, 1997.