But electric motors have a problem that mechanical 4WD don’t have. They don’t like to be immersed in water. Sealing the motors against water will be a big problem over long periods of time..........
For driving in waist-level water, the wheels could be driven through a train of gears to keep the drive motors elevated, and away from the water.
Even conventional engines don’t really do that well when immersed in water, unless specifically designed for that purpose.