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.
That's what I told my brother when he called me at 3 AM one morning when he'd left his truck on the beach that afternoon and the tide came in. It was worth it getting up and driving 30 mile to pick him and his girlfriend up and watching his truck bobbing up and down in the surf.......