Best Base Layer (2025): Goblin, Smartwool, and more

These soft and stretchy underwear are made from Capilene, an insulating fabric spun from 100% recycled polyester. Synthetic yarns perform on par with wool. Capeline is also quite comfortable, all while being light and quick-drying. Patagonia sells base layers in two thicknesses: midweight and heavier thermal weight. They come in men’s and women’s sizes, and the shirts are available in crew neck or zip-up collar. I tested it in the fall in Minnesota and San Francisco, so I wore the medium-weight version with a crewneck top.

Taking advantage of the precision that working with synthetic fabric offers, Patagonia has made some interesting design choices. The garment is smooth on the outside and has a subtly embossed diamond mesh pattern on the inside. The company says this diamond pattern creates tiny pockets that trap heat and help wick away moisture. It’s impossible to verify this claim, other than to say: The fabric kept me as warm as merino wool.

Like most Patagonia clothing, it’s a little looser than the same size from other brands. Although I tend toward base layers that are snug against my skin for maximum warmth, here I appreciate the extra room in the shoulders, in the groin, and under my arms. I wore it for two straight days on a boat camping trip — even while sleeping in it — and after showering a week later, I was commuting for another two days to and from my office. No chafing or bags, and the flex points never compressed. After each wear for several days, they smelled a little unpleasant, more so than wool in the same scenario, but much better than other synthetic materials I’ve tried. If you avoid wool due to allergies or because you avoid animal byproducts, these Fair Trade certified two-pieces are a solid alternative. —Michael Calore