Dawn dish soap works.

Dawn dish soap works. Rub a drop directly into the stain, let it sit for 10–15 minutes, then rinse with cold water. Repeat if needed.

For stubborn or set-in stains, try hydrogen peroxide. Dab it on, let it fizz for a few minutes, then rinse. Avoid bleach—it’ll damage the fabric and ruin the color.

Wash the swimsuit by hand with mild soap after. Heat (dryer, hot water) sets stains, so air dry only until you’re sure the stain is gone.

Don’t let sunscreen stains ruin your favorite suit.