After trying several other bag designs, this one provided the best accessibility with minimal wasted space when I used it in the polar regions (the Arctic and Antarctica) where weather conditions are less than ideal. The material is water-resistant, however, I found a waterproofing spray agent was needed to maximize its effectiveness in very wet conditions. Snow was not a problem. A waterproof cover was also effective, but markedly reduced accessibility. Zippers were easy to operate with gloves. Camera zoom lens greater than 300mm could have a fit problem, depending on the interior configuration, which I found very flexible for the three lenses I normally use, plus lots of room for filters, etc. This backpack model may be awkward to don/remove, depending on the bulk of the parka or other protective outerwear. In most instances, I found I could not wear the backpack in conjunction with a personal flotation device (PFD or lifejacket).
What's great about it: Contents easily accessible wearing gloves
What's not so great: Limited space for longer zoom camera lenses