In the time it took you to type that question you could have run a test and found out for yourself or looked it up in that Handy Dandy(tm) GAME GUIDE we are obviously wasting our time maintaining
under "MBT Unit Classes "
UnitClass 239=Hovercraft Hovercraft cannot bog down in mud and swamp like other vehicle classes and can move freely over land and water. They do not do well over Rough terrain and slopes and cannot enter treed hexes
Don