I'm headed out to the Grand Canyon this friday for a 1 week Grand Canyon rafting trip. I'm going with Grand Canyon Expeditions on one of their 8-day motorized rafting trips. I wanted to do an oar-raft trip, but given time and expense, this trip seemed like the best. I'm taking the following: Canon 5D Canon 10D (backup) 17-40mm f/4.0L 24-105mm f/4.0L IS 100-400mm f/4.0-5.6L IS Tripod, filters, cleaning equipment, etc... I'll be carrying the lot in a Pelican 1520 case, and use it to work out of on the boat. I'll just drop the 5D and the 24-105 in my waist pack and use that on any hikes. Equipment: I was wondering if I'm better off taking a 70-200mm f/4.0L with me instead of the 100-400? The 70-200mm is quite a bit lighter and easier to handle than the 100-400, though the 100-400 has the advantages of more reach and IS. Plus, I can use the 100-400 as a boat anchor, if need be. Shooting Tips: Any tips for shooting from a raft or inside the canyon? Positions on the raft best suited for photography? Best way to protect my gear while working from the raft? Opportunities to watch out for? I read Michael Reichmann's report of his trip down the canyon on Luminous Landscape, and looked at a few reports on the web, but am always looking for more tips.