Ships are a class of unit, and are trained at the Shipyard. They can only travel across water.
The Utility Trawler is an aquatic Worker that can construct AquaHarvesters and Sensor Buoys, and it gathers Food from Fish and AquaHarvesters. Frigates are scouts that can detect stealthed units, and also have a ranged attack. The Destroyer can crush enemy ships in close combat, particularly the Cruiser. The Anti-Air Destroyer can shoot down Aircraft, and the Cruiser is a long-ranged artillery unit that can destroy buildings from afar. The Transport Ship lets players transport land units across water.