As cool as it would be to make an underwater phone call, it's just not practical. It is, however, technically possible with the Sony Xperia ZR which is water-resistant for half an hour to a depth of five feet. Dust, scratch and shatter-proof too, it boasts a 4.6-inch HD display, 13 mega pixel camera, a 16x digital zoom, Walkman, album and movie apps and takes incredible pictures and video under the waves. It's one very smart smartphone.