While I'm no automotive expert, I do work for a large automotive electronics manufacturer. Most all of the electronics are sealed and designed to be spashed and sprayed by water as well as other nasties, BUT they are not designed for fluids under pressure due to depth.

The other problem is that you simply don't know what is underneath the water, so you can be trying to drive over hidden objects or encounter missing manhole covers. Of course running water is another story entirely and will take even the largest of vehicles for a ride.

You'd be much better off with a boat, though those hidden objects and debris could do a number on your prop.