Your outdoor clothing system starts next to the skin. Your undershirt ( commonly known in the outdoor industry as a “base layer”) has to be comfortable, non-chafing, and wick away sweat to the outer clothing layers so that you won’t stay damp. Being wet could be merely annoying, with the discomfort of shivering and chafing, or downright deadly if you’re in cold-weather conditions.

Two things we look for in a base layer are how lightweight it is and whether or not it has a hood. The latter isn’t necessary, but it’s supremely convenient on sunny days. There are a lot of undershirts and base layers out there; few are terrible, but few really stand out, either. These are our favorites.

Updated November 2021: We’ve added the Ibex Woolies Tech Crewe and replaced the Mountain Hardwear Ghee Hoody with the Ghee Zip-Top.

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