I enjoy all sorts of caches, but my favorites are ones with a reasonable trek into the wilderness because I enjoy taking pics of things along the way. Not sure what kind of camera you use, but if it is an SLR or DSLR, Lowepro makes an awesome small backpack called the Micro Trekker 200.
I have a DSLR and an extra lens but not enough to fill the bag. The compartments are all adjustable, so you have plenty of room for swag, a bottle of water or two (with a very tight cap!), extra batteries, snacks, etc. It's not too large and very lightweight. I poked a hole through a dishtowel and used a retractable key chain holder to attach it to the side. Now if I want to wipe the sweat off my brow, or the dust of of my camera I can just grab it, wipe, and let go. It snaps back to the pack. It is a little pricey at $80.