The stuff I read about earlier was considered hydrophobic meaning that it actively repelled water. British boffins perfect process to make any item '100% waterproof' The article I read earlier compared various hydrophobic levels with Rain-X being at one level and the new tech being in another league. This new nano tech doesn't make the water bead so gravity can make it roll off, it makes the water travel uphill to escape.

I could do it with a new phone that I wasn't using yet, but I use my phone too much to be without it for one day, much less several.

There are several different Inmersion Protection ratings http://en.wikipedia.org/wiki/IP_Code for different time periods and pressures.

Note that gear that you can go swimming with must have a high IP-rating or (preferably) be dedicated diver equipment. Real life is a bit harsher than lying idle in a poodle of water for 30 minutes.