Re: how can I save submerged outboard?
Best left submerged until you are ready to work on it. Then it needs to be in running position and constantly oiled. This is one time when you can't get too much oil in the carbs, so pour it on. Take the plugs out and turn the flywheel with a rope starter to pull the oil into the engine and lubricate the pistons, then add more oil through the spark plug holes.
You need to get every ignition component as dry as possible and then spray what you can with WD-40 to displace the water and slow or stop corrosion. This is one place where a air compressor is a real help.
The gearcase is sealed, so it should not have a problem.
If you have not done so, disconnect the battery and keep it that way until you are confident that everything is dry and clean.
When you are ready to run it, you will have to crank it a bit to get rid of the excess oil, but you may get it to fire by spraying premix into the spark plug holes and directly into the carburetor throats.
I'm sure there are a hundred other ways of dealing with the motors, especially from areas with sudden violent storms, so read on.
Edit: the quicker you get it running again, the less damage will be done.