There does exist a risk that, in the case of capsizing, the waders will fill up with water--and the fear is that the excess weight will drag you under and cause you to drown. The good news is that even when full, waders won’t cause you to sink. It’s basic physics: the weight of water filling the waders is equal to the weight of the water at the surface. (The good people over at SexyLoops did an interesting experiment to bust the myths about the dangers of kayaking with waders) However, if the waders are full of water, it’s going to be virtually impossible to right your kayak and climb on board. There’s just too much weight dragging on your limbs. If you’re in rough or stormy conditions where there’s a chance of capsizing, you’re better off wearing a wetsuit or drysuit. Waders are better for paddling calm waters with little chance of ending up in the water.