I know some of the reviews say that these bags aren't 100% waterproof and not what they are described as but you don't buy a cheap car and expect the same experiance as something more expensive do you?
I can't say that I've tried dropping them in a river and testing the water proofing, partially because I don't want or need too. But also because I can already tell you that whatever you've put on the inside will get damp.
However if like me you like the outdoors, camping, cycling or motorcycling these are perfect. I bought a whole bunch of them in different sizes and they've survived the worst of the Scottish weather and have kept everything inside them 100% dry.
So to sum up if Sailing, Kayaking, Canoeing are your hobbies don't be cheap go and buy a proper dry bag spend some money and keep your stuff dry.
For anything else buy these there great. Its worth noting that I since bought more as well in varying sizes.