Argo II

The Argo II is a boat the Hephaestus' cabin is building in order to travel to Greece and pick up Percy and other demigods at Camp Jupiter. [

History
During the Demigod Civil War, Bunker 9 was used as a command post for the Hephaestus cabin. One of the campers designed blue prints for a flying ship that may have been related to a prophecy, as there is a note stating "prophecy? Unclear. flight?" It is unknown who designed the blueprints for the Argo II, but they 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 Tía Callida. When he was five, he drew a picture of a flying ship in crayon. The ship was decorated with with flames and its masthead was the head of the metal dragon, Festus. Leo however lost the drawing in the wind.

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 the Bunker 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 Jupiter to meet them in the Forum.

Appearance
The ship is a magical trireme (A Greek warship with 1-2 small sails and 3 banks of oars). Its main weapon is a iron tipped battering ram meant to ram opposing objects. It also has Ballista and swivel-mounted crossbows, as well as landing gear in order to land, and metal plates to help shield it from enemy fire. It is unknown how it flies.