Thermal underwear works by managing sweat, not by being thick. Five base layers from…
🏆 Best overall
The Classic Thermal is Smartwool's midweight 100% merino crew in an interlock knit, with flatlock seams and a slim fit. It is warm enough for ski days and winter…
⭐ Best for active use
The 200 Oasis is Icebreaker's best-selling base layer: a 200 g/m² 100% merino jersey with underarm gussets, offset shoulder seams and flatlock stitching. It is lighter…
💰 Best value merino
Minus33's Chocorua uses 100% 18.5-micron merino in a 230 g/m² interlock knit — midweight warmth close to the Smartwool — at a noticeably lower price. It has a more…
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