What you need is sunblock/sunscreen. It comes in various forms. I use Avon Expedition in a spray can (my son's SO is an Avon rep), but I'll be researching other brands. It has a rating of SPF 30 and it's also an effective bug repellent. As long as the SPF rating is adequate, the brand is not a critical issue.
SPF (Sun Protection Factor) is the major parameter.
The SPF is the amount of UV radiation required to cause sunburn on skin with the sunscreen on, relative to the amount required without the sunscreen. So, wearing a sunscreen with SPF 50, your skin will not burn until it has been exposed to 50 times the amount of solar energy that would normally cause it to burn.Sunscreen
The article is very informative on the subject.
A few considerations:
• Extended exposure to water will probably wash some or all of it off, requiring reapplication. Resort pools and hot tubs usually require a shower with soap before entry, and that will certainly affect the blocking.
• When in the water, you are exposed not only to direct sunlight but to reflected light as well. This can drastically raise the exposure level.
• SPF refers to UV-B (UltraViolet B) exposure, the wavelengths that are responsible for the desirable tanning (and the undesirable scorching). Sunlight also contains UV-A, which does not cause reddening or tanning but does inflict nasty damage over extended periods. Broad-spectrum blocks work for both types, although some products labeled broad-spectrum are deficient in blocking UV-A.
• Too much UV-B blocking will retard the production of Vitamin D, a crucial vitamin for health. If you use a high-SPF product, consider D supplements (D-3 is a good choice).
May 25, 2010 -- A major consumers group has rated the sunscreens it says work best at blocking harmful ultraviolet A and ultraviolet B radiation that cause sunburns, wrinkles, and certain skin cancers.Best Sunscreens: A Consumer Reports Ranking
Consumer Reports Health tested 12 products and found four it says protect a touch better than the others.
The top four are:
• Up & Up Sport Continuous SPF 30, by Target. It is administered by spray and costs $0.88 per ounce.
• Walgreens Sport Continuous SPF 50. Also a spray. Cost, $1.33 per ounce.
• Banana Boat Sport Performance Continuous SPF 30. Spray. Cost, $1.60 per ounce.
• Aveeno Continuous Protection SPF 50. Spray. Cost, $2 an ounce.