Took this on a vacation to Cancun and had problems with it staying rolled down and sealed as we did a lot of water expeditions and swimming on the beach. I have used waterproof bags numerous times before, but always rented them, so i do know how to use them. I am a former Infantry soldier with jungle training that knows how to waterproof gear. I decided to purchase this one and was totally frustrated with its lack of holding air. No matter how much/little was put into this bag or how many times i rolled and folded it down with it clipped closed, it would find a way to unroll itself allowing it to deflate with almost all of the air escaping. When carrying with the strap (which is convenient) and holding it tight to the body or under the arm, is when i noticed it would unfold and let air out. Because of this, it is not waterproof but simply water resistant. I did use this in rain and in a light waterfall but refused to take it into any body of water or stream. I did not trust it to keep my personal belongings dry and found myself constantly checking and re-folding it. Bottom line! If it does not tightly hold air then water will enter. Where the bag and bottom meets, the sewing or stitching has become frayed all around and this was also a concern since it was used for only 5 days with no mistreatment. No misunderstandings! This bag is made of good quality material. Just needs some more work.