What I learned from Costa Rica, part 2

When I was preparing for this trip, I was considering to carry my camera gears in my Lowepro Nova 2 AW camera bag. Unfortunately, the bag is simply too small for everything I wanted to carry. I had to resort to a lightweight backpack and used old lint-free sweaters to pad the content of the backpack. It worked well. The backpack has wide shoulder straps so carrying my camera gears around was easy. I got the backpack from the Becel Ride for Heart for raising a certain amount of donations. It was a simple, lightweight backpack. It is not meant for camera gears but because the nylon bag fabric is waterproof (except for the zipper line) I decided to use it for my trip. Thinking back now, I probably should have used something else.

What I need for traveling with my camera gears is a waterproof backpack with flaps covering the zippers. If I carry the backpack on my back, it is possible for some thief to unconspicuously unzipper the bag and remove its contents in some busy foot traffic though. Therefore, it would be necessary to lock the zippers to deter theft. However, locking the zippers means unlocking them before use -- too inconvenient. It would nice if the zippers face your back then. This way, it would be extremely hard for the common thief to unzipper the bag let alone see the zipper.

Is there such a bag out there?