Another thing that you might notice if you wear a cotton base layer is an increased risk of B.O. Everybody gets it, especially during rigorous outdoor activities, but merino wool can actually help.

• Best affordable merino wool layer: Quince 100% Merino Wool All-Season Long Sleeve Base Layer for Women and Men • Best merino wool leggings: Icebreaker Women’s Merino Speed Winter 25-inch ...

We tested a mix of 12 wool and synthetic base layers to see which are guaranteed to keep you warm when temperatures drop. Two emerged as must-haves for this winter.

Also, because alpaca hasn’t hit the mainstream, base layer options are relatively limited. For the full rundown of how alpaca performs compared to merino, check out our Merino Wool vs. Alpaca: Battle ...

Merino wool has dominated the outdoor base layer market, setting the bar for warmth, breathability, and temperature regulation. Although merino has long been considered the best base layer material ...

Smartwool base layers are a must if you live in a cold climate or vacation in snowy destinations. The brand's apparel and accessories are all made of 100 percent sustainably sourced merino wool ...

On cold days, Merino wool keeps you warm, dry, and stink-free. These base layers—from Smartwool, Tracksmith, and other trusted brands—are great for runners.

We tested the best base layers for hunting from Sitka, First Lite, and more. These are the warmest mens layers we've worn, including merino wool and heated sets for cold weather.

We tested a mix of 12 wool and synthetic base layers to see which are guaranteed to keep you warm when temperatures drop. Two emerged as must-haves for this winter.