on land in minecraft, underwater physics will work, the bubbles icon will apear, in creative you will  float til your too high then , you wan slowly fall down, in survival, you float about 1 and a half blocks above the floors, the bubbles icon will apear but does not drain, no way of getting down either and in survival you dont float upand up, you just stay in the same spot. it happens in every world we try to join.