Seattle Sports Latitude Stuff Sack - Large, Waterproof

I've ordered 3 bags because of transparency and horizontal-wide opening and that is why it has 3 stars. But its "waterproofness" only for recreational use with occasional rain. It is NOT ready for serious kayaking,canoeing or rafting. Two bags were dropped downstream, were in the water about 30 mins. All clothing were wet up to the middle of the bag with closed, 4times securely rolled top and buckled. The closure is not tight enough. It LEAKS. I am rafting 7 years already and those are not the first bags I use.