That is not necessarily a good thing, as I once found out crossing a creek in my HMMWV (HumVee). Instead of keeping contact and traction with the creek bottom, it "acted as a boat," floating me off the crossing site and into deeper water before swamping itself and sinking.
So I am not surprised -- so long as the doors are sealed it should displace enough water to float, and if balanced should stay upright. But unless you can steer and have propulsion that is stronger than the current, it ain't a good thing.
I am left wondering if they tried doing a water crossing, accidently discovered this, and decided to make it a "feature."