A pair of thermal underwear pants are worn close to the body during outdoor activities in cold temperatures to keep you warm and comfortable. Thermal pants made from merino wool provide good insulation, are breathable, and naturally antibacterial. Synthetic materials are also a good choice because they are highly durable, quick-drying, and wick moisture effectively. For high-intensity activities in very cold temperatures, a base layer made from a blend of wool and synthetic materials is a good option as it keeps you warm while wicking away moisture. We offer a wide selection of thermal pants in various colors and classic patterns from well-known brands such as Icebreaker, Kari Traa, and Devold. Create your own thermal set with a matching thermal shirt.