The best underwear is the kind you don’t notice. When you do, it’s probably not doing its job. Finding out mid-run or mid-hike that your underwear just won’t stay in place sucks. A literal pain in the butt.

So with help from four other testers, who wear sizes extra small to large, I set out to find the best options for spending time outdoors. We tried 20 pairs of underwear—hipsters, bikinis, boy shorts, cheekies, and thongs—from nine different outdoor brands. All promised to be the ultimate you’ll-never-go-back underwear.

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