On top of the pyramid, our heroes see an orichalcum sphere in the water, engraved with an inscription. To escape giant crabs, they get on top of it and find an entrance, that leads them inside a submarine ship.
Just like the Solaris, they find pilot commands, and seek to activate them. A groove shaped like the Shimazu tsuba where they fit the key eventually awakens the ship. Tao tells them this vehicle is named the Thallios, from the inscription outside.
Thus begins an amazing journey under the sea, when the Thallios shifts to autopilot. They come to a ruined city made of huge stone blocks. Yet thanks to Esteban's medallion, the city rises up and the ruines make way for a wonderful underwater City of Gold, in which the Thallios enters.
Getting off, Tao reads the city's name on a statue holding a pearl which attracts the key: its name is Sundagatt.
Yet while they all go explore the City, Tao, who's still affected by his friend Ambrosius's betrayal, would rather stay alone and gets back inside the Thallios to study it.
As Esteban and Zia admire the City's water walls, Sancho and Pedro find a gigantic orichalcum block made of a myriad of small cubes. Nearby are laid gem-encrusted crowns.
When Esteban puts a crown on his head, the orichalcum cubes start to move.

Documentary: the huge blocks of stone of the Yonaguni underwater site in southern Japan, remnants of an ancient civilization, or natural phenomenon.
Kokapetl's Scoop: Giant crabs from Japan, spiders crab up to 3 m long and weigh up to 10 kg.

Characters (in order of appearance): Esteban, Tao, Zia, Mendoza, Pedro, Sancho, Kokapetl, Yoshi, Ambrosius.

Synopsis: Éric-Paul Marais
Script: Éric-Paul Marais and Didier Lejeune
Documentary author: Jean-Luc François
Storyboard: Aymeric Gendre
Artistic director: Fernando Lira
Assistant director: Régis Didry