Kyocera demoed its Torque G02 and Digno Rafre devices here at Mobile World Congress in Barcelona (though they were announced a few months before the show). The former is saltwater resistant, while the latter can be washed with soap.
Because salt is corrosive, most waterproof handsets are only protected against freshwater. The Torque G02, however, can withstand a dip in saltwater, so don't be afraid to take it swimming in the ocean.
Though these phones are still pretty niche, it's still to see Kyocera taking the steps needed to bring us towards the ultimate dream: being able to use our phones anywhere, anytime, without having to worry about them breaking.