I carry a quilted backpack. It has a zippered pocked on the back side of it that fits against my back which is where I keep my money so it's safe. On the inside of my backpack, I keep a bottle of water, camera, rain ponchos, cell phone, tissues and everything else that I think I will need (but end up never using!). It's very comfortable and doesn't feel heavy. It has a pull string to close it and then a flap that folds down over that and snaps. I would probably be able to feel it if someone tried to open it.
Donna