Keeping our equipment clean and dry in the field is an ongoing battle. If you store gear on a roof or rear rack, this issue moves front and center. I picked up an ARB Storm bag a few years ago and have lugged it to Africa, Southeast Asia, and Central America.
It is constructed of a PU Oxford weave with a PVC inner layer, seams are heat-sealed and taped, and rubberized panels cap each end. There are two zippered mesh pockets inside and a Velcro-secured pocket on the exterior. A semi-rigid plastic panel offers a stable platform for contents, and thick webbing around the closure is easy to grip when rolling it down. Four quick-release buckles, one on each end and two across the midsection, allow you to efficiently cinch the bag down to any size. When the closure is tightly rolled, Velcro strips line up and lock in place, reducing the possibility of snagging on other gear. There are two lashing hoops on either side, and the hand and shoulder straps have held up to heavy loads and numerous airports.
Although the Cargo Storm is not rated as a river bag, mine has endured downpours and being sprayed with oozy Central American mud, and I have yet to pull a pair of soggy socks from within. Available in 69- and 155-liter sizes, $94 and $120 respectively.
(CC) arbusa.com, 866-293-9078The ARB Storm bag is rated 4.1 out of 5 stars from 4 cusomter reviews on Amazon.