They call it "highly water resistant," but I'd challenge just about anyone to get water inside of one of Patagonia's Divider storage designs. I've kept a Great Divider in my skiff for years, and it's been the home of expensive video and camera gear. The only problem I've ever had with the Great Divider is that it didn't always fit in tight compartments without some squeezing, so I was very happy to hear that Patagonia is coming out with a half-size version of the product call the "Sub Divider." They've also dropped the double side handles in favor of a single, adjustable, removable, padded shoulder strap. And they've rounded the corners so that it is no longer a struggle to zip the lid shut.
If you absolutely have to have total waterproofness and think a few hundred bucks is a small price to pay for something that will keep your gear dry when it goes over some giant Amazon waterfall, be sure to check out Patagonia's redesigned Stormfront Pack. The new version features a new, easy-to-use waterproof zipper, a completely redesigned pod-to-harness attachment system, and an internal, padded, custom-fit gear case.
For anyone interested in more information on the Stormfront® Pack check out - http://www.wayupstream.com/2008/09/stormfront-pack.html