I heard a great story at the photo conference on the weekend. I attended a presentation by a couple of technicians from Canon’s camera service department on camera care, sensor cleaning and that sort of thing.
They had been talking about dealing with excess moisture exposure and moved on to the ultimate in getting you gear wet – full immersion. In most cases taking your camera for a swim is instantly fatal to the camera but if you know what you are doing, the camera can sometimes be saved. The problem is twofold. Electronic short circuits and corrosion. If your camera is turned on when it hits the water it is likely fried. If it is off, it might be OK.
The problem is, the second the camera leaves the water corrosion of all the metal parts, including fine electronics, begins. They were talking about a guy who dropped his camera into fresh water. He left it there, went and got a plastic bag and immediately brought the camera in to the techs in the bag that was now full of water. Just like taking a goldfish home from the store.
The Canon guys immersed it in a special solution that displaced the water and then got to work on the camera. The sensor is made up of layers that get penetrated by the water and it will always need replacement, but the guy managed to get away with a repair bill under $2000 rather than springing for a new $10000+ camera.
If you take it for a swim in the ocean however it’s a whole different kettle of fish. It’s probably destroyed. A small percentage of cameras may be saved by repeated dunking in warm fresh water to get rid of the salty water and then following the plastic bag tip. Personally, I’m happy to just pay my insurance bill each year.