I gave my otterbox a workout today. I tossed it in the hot tub and it floats. I dunked it a couple times then let it float for a few minutes. It didn't leak a drop, there was no moisture inside the case and I could even use it underwater.
You may think its weird to use a PPC in the hot tub but I love ebooks and I like to read in the hot tub, now I can. I can also surf the web and chat in IRC using my wireless from the hot tub. Plus the big reason I bought it is so that I can take my PPC into the woods without without worrying as much about wrecking it.