Perfect for sloppy exits and paddle-a-thons, Kokatat's Polartec Outercore Shirt is a great place to start if you want to retain warmth in less-than-warm conditions. And because this shirt is made from recycled Polartec Powerdry fabric, you'll have the full heat of a heavyweight top in a seemingly lightweight baselayer. Built to interact with your skin over long hours of repetitive paddling motions, the Outercore has flat-stitched seams that won't chafe your damp epidermis, leading to increased comfort that can make or break a multi-day river trip. After all, at mile 51 of the Middle Fork of the Salmon, you want to be nursing a beer in a hot spring, not nursing your tender, irritated contact points.