Yes the AT Pro is waterproof up to 10' just as Digging440yrs stated. I have used mine in the water countless times with no issues. Granted I've never been down in the water more than 4' with it but it still works just as well as the day I purchased it. Just make sure the battery O-ring stays pliable by using some good silicone grease from time to time. And after use I take the battery holder out so everything can air dry just in case.
Another item folks bring up from time to time is headphones are not necessary to be plugged in order for the control box to be waterproof either. This port is waterproof as is without the headphones if you choose not to use them.