There are numerous cases that allow the iPhone to stay protected near or even in the water, but the iPhone Scuba Suit casing for the iPhone 4/4S will actually allow the phone to go down to 15meters under the water. The company claims the casing will protect the phone from basically anywhere there is water, as it creates a liquid airtight barrier.
It provides easy access to the touchscreen through the touch-senstive gel screen and can allow users to snap photos – which is good as that is likely the only reason to bring your iPhone in the water in the first place.