Fibers alone, with or without hairspray, will not hold up when swimming if your head goes under or if you get splashed. Even being caught in the rain will destroy the illusion of hair. It is pretty damn good in the wind, tested this extensively (drove down an unused road several times at different speeds with my head out the window).
Dermmatch works great in water, if applied thoroughly. If you put it on dry in any spots, like I normally do for hairline, it'll look bad when wet, but if you put it on wet and are heavy with the product, it'll actually look good when completely wet. It will look bad when it dries, and if you dry your hair with a towel some product may come off and make it look terrible.
When I was at a concert and caught in an unplanned downpour, I simply didn't touch my hair and when I got home I was able to dry it, restyle it, and applied fibers over it. Fibers compliment dermmatch when doing touch ups.
