K. Locking biners work a bit better, 'cause some of the others can spontaneously open and lose things (keep one on your keychain and see how often you lose keys)

They do make plastic bags/housings that go over cameras - and they mostly work, the plastic does tend to turn color with age, and you don't get as good of results shooting through plastic - not to mention it's hard to use the buttons. And if you're in salt water, you get salt deposits all over the bag.

Same with the waterproof housings that canon makes for their camera - absolutely awesome if you're snorkeling or diving - but bulky and almost always covered with salt in a kayak. (expensive as well)

I put a little bag of dessicant salts in my drybags for electronics, 'cause you get condensation of moisture inside the bag - and that's killed my cell phone a few times.