The Argo II has been in 5 out of the 6 books in The Heroes of Olympus series.
- The Lost Hero (mentioned and hinted in Leo's childhood crayon drawing)
- The Son of Neptune (seen in the end of the book)
- The Mark of Athena (major variable and weapon)
- The House of Hades (major variable)
- The Blood of Olympus (major variable)
Note: It also appeared in the short story Leo Valdez and the Quest for Buford briefly
The Argo II was created for water transportation and air transportation across the earth. Its purpose was to provide the demigods from the Prophecy of Seven a way to travel quickly. It was named the Argo II after the first Argo ship; the one consisting of the infamous Jason and the Argonauts. The Argo II docks at Camp Jupiter, in San Francisco, and the demigods currently aboard; Jason Grace, Piper McLean, Leo Valdez, and Annabeth Chase, attempt to make peace. This backfires when Leo is possessed by an Eidolon. While under the Eioldolon's control he fires on New Rome which ultimatley causes an outbreak and the Greeks are attacked by angry Romans. Hazel Levesque, Frank Zhang, and Percy Jackson are forced to escape on the Argo II along with its original members.
- Leo Valdez
- Piper McLean
- Jason Grace
- Frank Zhang
- Hazel Levesque
- Nico di Angelo (part time)
- Percy Jackson
- Annabeth Chase
A Greek demigod son of Vulcan, Leo drew this kind of ship during his childhood. In The Lost Hero, Aelous, the master of the Winds told him that this will be the key to his success. It was his destiny to always build this "weapon." In The Lost Hero he recalls drawing the boat as a child with crayons and refers to it as the crayon drawing of destiny.
- The Argo II appeared on the cover of The Mark of Athena (UK).
- It is currently unknown what becomes of this massive warship after the war with Gaea