|The Xperia Z [Photo: Sony]|
This water-resistant feature is relatively common in Japan, but has not been included in many top-end smart phones released elsewhere.
The Xperia Z can also record HDR (high dynamic range) video, a facility borrowed from its camera division.
One analyst said it was evidence of Sony Mobile making progress but added "it still had a mountain to climb".
The Japanese company announced it was taking control of the smart phone unit - which had previously been a joint venture with Ericsson - in October 2011.
Sony posted a full-year loss of 56.7bn yen ($5.7bn; £3.5bn) in May and has continued to lose money over subsequent quarters.
The Android-powered device was unveiled at the Consumer Electronics Show in Las Vegas.
Sony says the handset, which has a 5in (12.7cm) screen, is capable of being submerged in water of up to one metre (3.3 ft) in depth for 30 minutes.
"If you want to want to sit in the bath and watch an HD movie this is the device for you," Sony Mobile executive Steve Walker told the BBC.
"You can take it in the shower if you want, or more usefully if you get it dirty you can wash it under the tap."