Posidon X

From DALpedia

The Posidon X is the flagship of the Kingdom Of Tjed. Sporting a long design with fin-like protrusions on either side, it is quite fast. It holds a gambling hall and guest chambers and sports the unique ability to dive underwater like a submarine.

It appeared in Chapter 8, when King Henri went to get Ven to come back to Tjed. Ven traveled on the ship, along with Zeros', Duilin and Rink.