FAQ7: What should I do if I crash in the water?  

For the most part it is less damaging to crash in the water than into a runway. Water IS a bit softer than concrete or even sod.  
The first consideration is that you have to go get your plane.  That was in FAQ6.  
The second consideration is, once you get it back, getting it dried out.  

If you have sealed the wood inside the fuselage you are ahead. Thje balsa will not be waterlogged.  
If the plane just took a dunking, give it a thorough inspection.  Check the radio for functionality.  See if there are droplets of water inside the protective baggie on your transmitter.  This is the advantage of high-wing planes: they float on the wing and the fuselage doesn't get much water inside.  The DO float nose-down, so you likely have water in your motor.  If there is any doubt about the electronics,  open the receiver case and blow the moisture off the circuit board with a can of the computer dusting stuff.  Remove the battery and make sure the foam is not soaked.  Remove the paper towels we talked about in FAQ5 and replace them if they are wet.  Blot any water droplets inside the fuselage.

2-cycle motors:  remove the glo-plug.  Pour out any water you can by(1) pouring any water out of the muffler and (2)  holding the plane upside down and cycling the prop manually.  When you are convinced there is no more moisture in the motor, Replace the glo-plug, start it and let it run for several minutes.  This flushes the water droplets out of the bearings, rings, etc.  
A good shot of after-run oil, Corrosion-x, or Marvel air tool oil is a very good idea when you put the plane away.   If the plane is too badly damaged to start and run the motor, at least flush the motor with fresh fuel and after-run oil.  Likewise, dry the electronics-don't put it off until you are not mad about crashing unless you are independently wealthy.  

4-cycle motors:   There is really not an effective exchange of the atmosphere in the crankcase of a 4-stroke and water that gets in tends to stay there.  Bearings rust, and your Mastercard takes a hit.  Anyway, flush the crankcase throught the breather nipple with a coupla' shots of fresh fuel.  Hold the motor so the breather nipple is at the lowest point and flip the prop so all the fuel is squirted out.  I ruin lots of shirts this way.  Follow up with some after-run oil .  Obviously, before trying to start it, rotate the engine carefully through several revolutions to be sure there is no water in the combustion chamber.  Remove glo-plug, drain,  and spin with the starter if you suspect water inside the cylinder.  

Electric power:  Likely if you have trouble it will be with the ESC.  Dry the ESC thoroughly unless it has already gone poof. Motors: Blow the water out, lubricate the bearings, and run the motor.    Dry the battery packs and other electronics just like if you have a fuel-powered plane.  

If it's just been dunked and you have it dried out, go back to flying and have a good time.  
If the plane is damaged, take it home, take it apart, and dry it out on the workbench.  You can open up the servo cases to see if there is water inside. Pressurized computer cleaner, compressed air, or even a hair-dryer all get rid of the water, do it before the water corrodes anything and likely you will be able to use the electronics.  Get the wood of the airplane dry and assess whether it is repairable.