The World Government's intention was simple: it wanted to continue maintaining its Seastone trade with Wano Country.
Seastone was an extremely rare mineral produced in Wano Country. It was essentially a crystallization of the sea, its composition highly similar to seawater—one could even call it the solid form of the sea.
Its effects were the same as seawater: it could sap the strength of Devil Fruit users until they were unable to use their special abilities. In fact, its effects were even stronger than seawater's, so it could be said to be the natural enemy of Devil Fruit users.
And the craftsmen of Wano Country possessed ancestral techniques for processing Seastone, as well as controlling its purity to achieve different levels of restraint.
For example, it could render someone completely powerless and unable to move, or leave them barely able to work while still unable to use their abilities, and so on...
Apart from that, the navy had also developed a method of attaching Seastone to the bottoms of warships in order to deceive the Sea Kings' senses in the Calm Belt, allowing ships to pass safely through the Calm Belt.
The geography of this world was bizarre. Two rings, one horizontal and one vertical, divided the sea into four parts. Both sides of the Grand Line were wrapped in the Calm Belt, where enormous numbers of super-large Sea Kings lived.
So-called super-large meant bodies at least over a thousand meters long, even exceeding five thousand meters. Even a single one was troublesome for a navy officer to deal with, let alone when there were so many of them.
Without Seastone technology, travel between the four seas could only be connected through the Red Line, or by passing through Reverse Mountain at the entrance to the Grand Line. It was