It was a tight fit. The float planes that fly into some of the remote locations in BC have strict weight restrictions. If you are over the limit (pretty easy to do if you're a photographer) expect to pay an added fee for the excess weight.
As always, I had my handy travel compressor bags to save space. I was visiting a temperate rainforest in late September, and packed accordingly. Warm hat, gloves and thermal underwear were musts, along with a good waterproof rain jacket and rain pants. Rubber boots or hip-waders are needed as well, as there were several instances in which we had to make "wet landings" during shore excursions (stepping into the shallows rather than on dry land).
Sun glasses and sun screen are good to have, just in case (you never know, the sun could show itself). Also be sure to bring a book or some other form of entertainment, in case you're prone to cabin fever.
Gear was mostly packed in the LowePro PhotoTrekker AW II, but I also brought along my ThinkTank Skin belt and pouch system, which came in handy during excursions on the Zodiac and onto shore. You can read my additional notes on this system and some of the pouch options in my Costa Rica 2008 summary.
Some notes on shooting in the Great Bear: It is generally a dark environment, due to typically wet or overcast weather and the wooded surroundings. A tripod, good digital camera body that handles high ISO well (e.g., Nikon D3, Canon 5D Mark II, Canon 7D) and a 2.8 and/or Image Stabilized lens are all tools that can help produce better photos in tough conditions. Much of the exploration along inlets and rivers is done in the Zodiac. I had success using my tripod as a monopod for my 500mm lens and shooting while seated along the sides of the Zodiac, and other times by propping the lens on the edge of the Zodiac. This is feasible only if there's room and if you have understanding fellow travelers. I was lucky to have both.
A good rain cover for your photo gear is a necessity.
Canon 40D, 20D
Canon 100-400IS (the 70-200mm 2.8IS may have been a better option)
Canon 24-70mm 2.8
Canon 1.4x teleconverter
ThinkTank Pixel Pocket Rocket
Extra Batteries, Memory Cards
Lens Wipes/Brush, Polarizer, Graduated Neutral Density Filters
Epson P-5000 Storage Device
Rain covers for camera & lenses
Powerstrip & battery chargers