Check out Sony's brandnew Android smartphone the Sony Xperia ZR, which is designed for underwater shooting. Howerver, you can only use it in fresh water.
It comes with a 4.6 inch screen full HD, 13 megapixel camera, 1.5GHz quad-core Qualcomm Snapdragon processor, 4G LTE, and 2GB of RAM.
Xperia ZR Specification:
Display: 4.55 inches 16 millions colours
Operating system: Google Android 4.1 Jelly Bean
Processor: 1.5 GHz Qualcomm Quad Core
RAM: 2GB RAM
Storage: 8GB internal storage, microSD expansion 32GB
Connectivity: 2G, 3G, 4G, Wi-Fi, Bluetooth 4.0, microUSB 2.0 and NFC-enabled SmartTags
Camera: 13 megapixel fast-capture camera with Exmor RS
16x digital zoom with auto focu rear camera with LED flash, VGA front unit
Will be available in black or white.