As long as the bag is not completely submerged, whether in rapids or other wet situations, it flawlessly keeps the contents dry, protecting ... across the body. 20L, 30L, 40L come with double ...

And while there are plenty of rollbags around, with a variety of features, this one from Lomo is of incredible value and does a great job of keeping your gear dry ... in either 20L or 40L flavours.