There's no such thing as waterproof or sweatproof. It's technically impossible for a sunscreen to be waterproof or sweatproof, says the FDA. Instead, sunscreens can be water-resistant, but only if they retain their original SPF (Sun Protection Factor) after 40 minutes in water.
Credit: Ian McDonnell / Getty Images
The 2014 Adventure Issue
From Iceland's Highway 1 to Utah's Canyonlands, an epic itinerary for modern explorers.
Plus: Building a Bigger Action Hero
ON NEWSSTANDS NOW
The Interpreters We Left Behind
The Rise of Cyclocross
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