For wet and slippery missions, there's Cairn 3D Pro II, the ultimate adventure sandal outfitted with our new Hook-heel strap, extra-sticky Vibram® Megagrip outsole, and moulded 3D footbed. The Pro II G-hook and loop system locks in the heel strap like it does the front, for a super secure fit that won't fail in the frothiest rapids or thickest silt.