I use the Ortlieb messenger backpack and I can testify for its one quality that was the one quality that made me buy it. It is indeed totally waterproof. I must have that because on many days the bicycle is my only reasonable method of transportation, and if it is raining I have to go no matter what. Its "negative" points are that there are no external pockets, and no place to clip one of those little blinking lights, if one has a need for those features. I myself do not. The only really annoying feature is that it is so deep and so dark that if I want to find something that has migrated to the bottom I almost have to put on a headlamp and dive in head first. But that is minor. I do like it, and if it ever wears out (seems unlikely) I probably would get another.