A Boat can be upgraded into a Ship for five stars, and a Ship can be upgraded into a Battleship for 15 stars once Navigation is researched. (The total cost of upgrading a Boat into a Battleship is 20 stars.) Upgrading a naval unit does not heal it.
|Land units: Warrior, Rider, Archer, Swordman, Catapult, Knight, Defender, Mind Bender, Nature Bunny|
Naval units: Boat, Ship, Battleship
Super units: Giant, Crab, Dragon, Gaami
Aquarion units: Amphibian, Tridention
∑∫ỹriȱŋ units: Polytaur, Navalon
Polaris units: Mooni, Battle Sled, Ice Fortress, Ice Archer
Removed units: Scout, Guard Tower