From the handbook (Page 10):
Built by Navy Yard.
Mobile unit - Ship - Weapon: Armored gun turret.
Most of Creon is comprised of coastal regions and treacherous waterways, so this craft is essential to the maintenance of their empire. This steam vessel is covered with iron to protect its occupants and to lend it a menacing air. The Stern Wheeler is Creon's preferred transport for large numbers of troops.
Note: The Stern Wheeler is the only type of creonite ship that can attack both flying and ground/naval targets.