After spending childhood summers, birthdays, and pretty much any available moment on beach vacations, one of the biggest lessons I’ve learned is to always, always pack a water-resistant sunscreen . But what exactly makes a sunscreen water-resistant, and why don’t we call it waterproof? I asked a dermatologist to answer that and more before compiling a list of options aligned with her guidance. Want more from NBC Select? Sign up for our newsletter, The Selection, and shop smarter. The list below