Check out Rev Packs, he's been making these bags for a long, long time, I've now been using them for almost three years, very rugged, even when going down ( believe me, I know ) waterproof, the top part of the bag expands, and the best thing about them is they can be used as a cooler to carry beer with ice !
I would buy them again in a heart beat, and the owner is a real nice guy that stands behind his product, which is made right here in the USA.