If you drop your camera into water, there's a few things you can do to improve your chances of camera survival.
Immediately turn the camera off. Then, take out/off accessories such as the battery, memory card and lens. Lay them out individually to dry. "Dump" any excess water out of the camera if it's full.
Air drying the camera is the best option, but if needed, you can use a hair dryer on a low setting for short amounts of time. The camera will take days to fully dry out on the inside. Do not turn the camera back on until you are positive that it is completely dry on the inside (any leftover water could fry the circuitry).
If you happened to drop the camera in salt water, then after removing the accessories, before drying, rinse the camera in distilled water to remove the salt. *This is if the camera was submerged, and not just if a little sea spray got on it.
Adding silica packs (or rice) nearby your camera, in your camera bag, or put together with the camera body and/or lens in a Ziploc bag will help to absorb any extra moisture.
Obviously, you want to try to never drop it in the first place, so solution: use a strap!