Argo II

The Argo II is a flying boat built by the Hephaestus' cabin in order to travel to Greece and to pick up Percy Jackson and other demigods at Camp Jupiter. It's currently manned by Annabeth Chase, Leo Valdez, Piper McLean, Jason Grace, and Gleeson Hedge

History
During the Demigod Civil War, Bunker 9 was used as a command post for the Hephaestus cabin. An unknown camper designed blueprints for a flying ship that may have been related to a prophecy, as there is a note stating "prophecy? Unclear. flight?" While the designer was never known, the name of the blueprints led to revealing the name of the ship—Argo II. The creator never made the ship and eventually the bunker was abandoned. Decades later, Leo had a dream about the Argo II, made out of flames, when he was two while he was still under the care of Tia Callida/Hera. When he was five, he drew a picture of a flying ship in crayon. The ship was decorated with flames and its masthead was the head of the metal dragon, Festus. Leo, however, lost the drawing in the wind though much later it was returned to him by Aeolus.

The Lost Hero
Years later, Leo discovers he is a demigod and is sent on a quest to rescue Hera, queen of the gods. Before they leave, Leo discovers Bunker 9 after repairing the bronze dragon that he names Festus. He sees the blueprints for the large ship he drew when he was younger, but focuses on adding a pair of wings to Festus. While visiting the god Aeolus to ask for help, he returns Leo's drawing of the Argo II (not named at the time) to him claiming that everything lost in the wind finds its' way to him. Leo takes the picture and puts it in his pocket without showing Jason or Piper.

After the quest is completed, Leo shows Bunker 9 to the rest of Cabin Nine, including the Argo II blueprints. He shows them the picture of the ship he drew when he was five, and feels that the ship is tied with his destiny and says he is going to build it, with the head of the recently destroyed Festus as the mast head. When Leo pulls out his crayon drawing, everyone compares it, and they all find that the drawing and blueprint are the same. Then, he and the Hephaestus cabin start to build it, to sail to Camp Jupiter.

The Son of Neptune
Percy Jackson has dream visions of Jason, Piper, and Leo finishing the ship and welding the head of Festus to the mast. However, the ship's samophlange breaks and Leo says it could take a few days to fix. At the end of the book, the ship appears on the horizon and Percy gathers Camp Jupiterto meet them in the Forum after he is elected Praetor.

Appearance
The ship is a magical trireme with one sail and probably a few banks of oars. It's a 200 feet (61 meters) long with a bronze hull, and a flaming dragon head at the top of the mast. Two repeating crossbows that could fire explosive bolts powerful enough to blast through concrete are the main weapons. It has some kind of break and probably a landing gear but it is unknown how it flies. Both Leo Valdez and Jake Mason describe it as "A spankin hot war machine", though Jake says this as he examines the old blueprint for the ship. The controls consist of a keyboard monitor, aviation controls of a leer jet, dubstep soundboard, and Wii remotes and sensor which control different aspects of the ship.