Anything that can block the UV rays from the sun is going to protect your skin and so it's important to try to cover up as much as you can and still be comfortable to protect these large areas of skin.
If you're going to be on the beach or you're going to be in a pool, you want what we call sun-protected swimwear. It's basically something that you can wear in the water and you can also wear before you get in the water. It's going to essentially block all the UV rays. If you're getting any redness or tanning you know that some sun is getting through.
So what protects the skin from the sun when using UV protecting clothing. It's the fabric, any fabric that you can hold up to a light and not see the shape of the bulb is giving you protection from the sun.
Many of the UV protecting clothing for sale is made from polyester. UV protecting clothing is usually not enhanced with any chemicals. The fabric should be a thick tight weave.
When your vacationing and your child is spending lots of time on the beach it's a good idea to wear clothing that blocks the sun and sun screen on exposed skin. There are two types of sun screen, one that contains minerals, either zinc oxide or titanium dioxide. These minerals reflect all the UV rays, the sun just bounces off, they are long lasting and hard to wash off.
The other product is a chemical based sunscreen, these sunscreens absorb the UV rays, especially the rays that cause sunburn. Some deep rays will get through and you can still get some tan, these products need to be reapplied often. The mineral type is slightly more expensive, but does a much better job.