A base layer long sleeve t-shirt is essential for regulating body temperature and wicking moisture away from your skin during the Camino. Choose a shirt made from high-performance, moisture-wicking fabrics like merino wool or synthetic blends. Look for features such as flat seams to prevent chafing and a snug fit to enhance layering. A long sleeve design provides additional warmth and sun protection, while breathable materials ensure comfort in varying weather conditions. Opt for a shirt with antimicrobial properties to reduce odors during extended wear.