Elon Musk recently confirmed that his cars float well enough into a boat for short periods of time, even with some thrust and control from drivewheel rotation! He just saw a recent video of a driver taking his Tesla Model S through a flooded tunnel. The Models S calmly passes by disabled 'flooded' ICE cars. It is probably safe to say that it was sealed from internal flooding (Elon Musk did say their Tesla's are bio-weapon sealed) and the batteries were safe from water intrusion. Wondering when the next fully 'submerged' Youtube entries show up!