The top is one of those flip top lids that make it easy to get to your gear. It has some type of flap there that helps keep moisture out. I wouldn’t call it rainproof but I have read about several instances of people getting caught in the rain and everything in the bag staying nice and dry. If you look along the top you’ll notice a little Velcro strap to be used when you want to roll up the flap to allow for faster access of the bag contents. In front of the bag you can also see to additional pockets for more external storage. The one on the left has a couple of pockets sown into it to hold compact flash memory while the one on the right has a few for pens, AA batteries or lens pens. Either pocket could hold a passport, a wallet and a few other things. Besides, pens and batteries I keep all my manuals in one.
From National Geographic NG-2475