Originally Posted by concentric
Some cameras (like my Canon SD700 ELPH) have "waterproof" housings that the manufacturers sell that work pretty well. I have one and have used it snorkeling quite a bit. It adds some shock-resistance to the package as well.
You can see some examples here:
Actually, I think most point and shoot manufacturers have housings now. Makes selecting an inexpensive scuba photo rig kind of tough (luckily, or unfortunately, I've decided to jump towards an SLR package when I can afford it. Big bucks.)
But, the housings for the point and shoots tend to be bulky, and will leak if you don't perform some basic maintenance after each use and take care in assembly. They are relatively inexpensive, though.