There's a company out there called liquipel that puts a coating on your phone that cannot be seen. I just checked their website and of course they hav the youtube videos showing a phone treated and it working under water, here's one with a Thunderbolt:
[video=youtube;7Ama47RGdL4]http://youtu.be/7Ama47RGdL4[/video]
They charge 60 bucks to do the Maxx which is bout the same cost as an otterbox. Check it out.