Undercover Warmth Long-Johns. Thermals. Long underwear. Whatever you like to call them, these classic undergarments that keep us warm from shoulders to ankles are crucial in cold climates. The Swedish designer, Hanna Anderson, offers tons of styles in organic cotton: There are also some great versions from The Organic Company, and Rawganique. Patagonia offers a 54% recycled poly baselayer thermal, and Kenyon offers a recycled poly-bamboo blend.