Thicker than a thermal, and just fine on its own, or rocking it as a base layer. The Seawool Nep Crew is warm and insulative, but allows for air circulation to keep you from getting stuffy. Wear it solo with a pair of jeans, or rock it under your favorite flannel on a brisk fall day. Seawool Seawool is a sustainable fabric that's built to last using recycled plastic bottles and oyster shells. Seawool is warm yet breathable, and has natural antimicrobial properties that keep it from developing a smell. Seawool is static resistant, ridiculously soft, and looks great with just about anything.