Nautilus ( Final Fantasy XIII ) Nautilus is a location in " Final Fantasy XIII " . Known as the capital of entertainment on Cocoon , Nautilus is the home of the popular Pompa Sancta parade , and it houses an amusement park featuring tame chocobos of a smaller build than their Gran Pulse variety . It is known as the " City of Dreams " , and is shaped similarly to a Nautilus shell . Nautilus is an unrevisitable location and comprises the game ' s eighth chapter . Datalog . " Centered around the ever - popular Nautilus Park , the ' City of Dreams ' is essentially a giant fairground built by the Sanctum for the amusement of Cocoon ' s citizens , Tourists visit from all corners of the world , keeping the city busy and bustling all year round . " " Nautilus Park is the crown jewel of the Sanctum - built City of Dreams . it houses numerous attractions constructed with the latest technology , but the true stars of the park are the chocobos and sheep found in the family - friendly petting zoo . " " With the wilds of Cocoon crawling with all manner of vicious beasts , people find the presence of the docile park animals to be a rare and reassuring change . " Story . Sazh and Vanille arrive in Nautilus after leaving the Sunleth Waterscape . They spot an advertisement for the Pompa Sancta Parade followed by breaking news from Palumpolum , showing taped footage of Lightning , Snow , Hope , and Fang attacking PSICOM troops . Vanille recognizes Fang , but says nothing Sazh asks about it . They attend the Pompa Sancta Parade , which tells the story of the War of Transgression between Gran Pulse and Cocoon . The two visit the Chocobo Corral in Nautilus Park , where Sazh announces he will turn himself in to PSICOM to see his son for one last time . Vanille tries to dissuade him and is about to admit her involvement with Dajh becoming a l ' Cie , when they are pounded by bullets from PSICOM troops . The two escape to the Clock Tower where they destroy a Midlight Reaper and Sazh comes face to face with his son who turns to crystal . Jihl Nabaat appears and tells Sazh that his son ' s Focus was to find Pulse l ' Cie and reveals Vanille and Fang were responsible for his son being turned into a l ' Cie . Vanille runs away in tears , and Jihl encourages Sazh to pursue her . He follows her to the Fiendlord ' s Keep where Vanille hallucinates an image of Sazh shooting her . Sazh aims his gun at Vanille but his Eidolon Brynhildr appears and the two defeat it together . After the battle , Sazh again turns his gun on Vanille , but is unable to shoot her , acknowledging it will not help his son . Sazh turns the gun on himself but is unable to end his own life . Jihl arrives with PSICOM troops and captures both Vanille and Sazh telling them that the Sanctum would build a memorial in Eden and use Dajh as a monument to " the boy who saved Cocoon " . After Jihl renders Sazh unconscious he is carried away in a coffin and Vanille follows behind in Purge attire . The two are taken aboard the " Palamecia " and placed in confinement . Quests . Flight of the Chocobo . In the Chocobo Corral , the player must find Sazh ' s chocobo chick . Musical themes . The themes " Nautilus " plays in Nautilus , while " Chocobos of Cocoon - Chasing Dreams " and the battle theme , " Feast of Betrayal " play in Nautilus Park . A piano arrangement of " Nautilus " is included on the " " album . Etymology . The park ' s name may derive from the " Final Fantasy III " airship of the same name . The city is also shaped similarly to a Nautilus shell .