The Skin Cancer Foundation recommends using a broad spectrum (UVA/UVB) sunscreen with an SPF of 15 or higher every day. If you’ll be outdoors for a longer period of time, try using a water-resistant, broad spectrum (UVA/UVB) sunscreen with an SPF of 30 or higher.
Remember: Sunscreen before your suit
If you want extra protection from the sun, the Skin Cancer Foundation suggests applying your sunscreen before you put on your bathing suit.