I want to take something bigger than my trusty Nikonos on my next canyoneering trip, but I'm having a hard time finding a suitable case for my LF gear. I'd most likely bring a Cambo Wide, extra lens, Kinematic back, light meter, a few filters, and small tripod. The case(s) would have to protect from bumps and abrasions from the rock walls, splashing water and short-term immersion. And because it will be riding on my back, it needs to be light, compact, and easily lashable to my pack. For the tripod I'd bring an old metal Linhof sans head, so that can get wet with no issues; the rest will have to be protected.
The typical Pelican etc. cases are waaay too heavy, and "dry bags" are laughable, in my experience. I've located the manufacturer of these dry kegs (http://www.summithut.com/products/canyon-keg/), and they're a possibility. They are strong and light and waterproof; their issues are that the opening is quite a bit smaller than the diameter, and that they go from too small (like the ones pictured) to huge without any intervening steps. The cylindrical shape gives it strength and waterproofness without much weight, even if it means some wasted space.
Any suggestions or products that I should consider? Thanks!