based on this, your hunch is correct..
That video is crazy. Repeated dunks in the water at five minutes a time and then at maximum depth the river will allow (35 feet) and it is STILL alive and working - while not 100% perfect - for a non waterproof phone that is astonishing. How many people would trust a waterproof case at that depth for that length of time?
Bravo Apple. You can take it to the beach/pool/around water without panic. If it falls in water a small in and out dunk is not going to do it any harm. I am imaging the crazy photos you can take with that + dual camera now.
I have gone from "meh" about the phone to seriously desiring it, all thanks to a few Youtube rich kids trying to obliterate the iPhone in water.