There's also a small group of waterproof packs out there. SealLine's Boundary Pack ($60 in the 65-liter size; www.seallinegear.com) is essentially a drybag with straps attached. Not a great load-carrier, but more than adequate for lugging camera gear on short portages. Again, I'd put my camera inside a traditional bagmaybe Lowepro's holster-style Rezo TLZ 10 ($25; www.lowepro.com)then place that whole deal inside your drybag or drypack. That way you're sure to have both padding and waterproofness.
Eureka! took a stab at making waterproof packs a few years back, and although they've discontinued the line, you can still find some examples. Do a search for Eureka! Storm Chaser Pack and you'll find some for $70it's basically a vinyl pack with sealed seams and a roll-top closure. It'll shed rain, paddle splashes, and the like, and can withstand short immersion.
Lastly, consider a bear barrel, designed to keep bears from smelling or getting at your food. Sturdy and nearly 100 percent waterproof. The BearVault 250 ($67; www.bearvault.com) is a good candidate, with 430 cubic inches of space. Put the camera case inside, screw the lid shut, and you're all set!
For the Web's best selection of haulers, check out Outside Online's all-new Backpack Buying Guide.