Madame Shyarly has prophesied that Luffy will destroy Fishman Island, but before that, I will discuss the road to Raftel and One Piece and how it all ties with why Luffy will destroy Fishman Island.
It all starts with a simple question: why did Gol D. Roger travel twice the Grand Line?
Roger and his crew were in a big hurry as Roger didn’t have much time and knowledge of where Raftel and One Piece were.
Gol D. Roger and The Voice of All Things
Gol D. Roger listened to “The Voice of All Things” to guide him to the One Piece. He first traveled the grand line and discovered the story behind all the Ponegliffs.
After he found Raftel, his journey should have ended, but as he was an adventurous type, just like Roger’s crew, he sees the same thing in Luffy; he went to every single island to leave clues on the Ponegliffs to guide a worthy successor after him.
He wanted to go back to check their interpretation, as they didn’t know Ohara scholars. Also, the clues on the Ponegliffs were left to fulfill the destiny of the Void Century, which he couldn’t do as he was becoming weaker from his sickness.
After leaving the clues on the Ponegliffs, he decided to disband his crew a year before his execution and gave them a specific task; two studies came to mind.
The first is to find a D-worthy successor, and the second is to remain stationary at crucial points where they can guide and give clues to him to the next adventure and find the One Piece.
This brings us to where Raftel’s location is. In the image above, you see Raftel next to Reverse Mountain. Many theories suggest that Raftel is a journey beyond the end, meaning that Raftel was just in front of them before the trip started.
Just after going up the reverse mountain with Merry and finding Laboon, Crocus gives them the most significant hint: “And the name of the island at the end of the route is… Raftel.” And he concluded by saying, “It’s the last point on the Grand Line.”
This means the island is found next to Reverse Mountain, but you must go to the Grand Line to find it out. What strikes me most is how one crew can arrive at Raftel and then go back to travel the grand line.
There is no way to climb up the Reverse Mountain, and the only option is to travel by the calm belt, which is the most probable way he did it as he had “The Voice of All Things” and could command Sea Kings to help him cross the calm belt either to the North or South Blue and then go up Reverse Mountain.
In all treasure maps, X marks the spot where the treasure is. Raftel is close to Reverse Mountain; the 4 Red Ponegliffs pinpoint the location of Raftel while the other Ponegliffs tell the story of the Void Century.
This story has one hole: why does Gol D. Roger want a successor? Why does he need to inspire pirates to venture into the sea, and what is so essential on Raftel that will change the course of history?
Ancient Weapons and Truth About D. Clan
The answer lies in Raftel, where the Rio Ponegliff resides, and this Ponegliff will answer all the questions.
First, it will tell us all about the Ancient Weapons and how they were used, who is responsible for the Void Century, and you shouldn’t be surprised to know that the Nobles and the 20 kingdoms are accountable for that.
Secondly, on the Rio Ponegliff, there will be a shocking truth about what the D stands for and how the Nobles killed almost all of them just like they did in Ohara with the Buster Call, making Luffy and the Strawhats mad.
His only option is to destroy Mariejois by returning to the Grand Line and facing the nobles and the world government. Similarly to the Enies Lobby burning the WG flag, he, alongside his allies, will destroy Mariejois with most Nobles.
This is where Fishman Island comes into place; there are two options for destroying it.
The first one is that as Fishman Island is very close to The Holy Land of Mariejois, it will suffer the aftermath of the destruction of Mariejois by tons of rock falling from above and hitting the air bubble directly, ing Fishman Island for good.
Do not forget that Gorosei, the head of the World Government, resides in Mariejois and does not know this will be the most significant war. According to an interview with Oda on One Piece, some effective destruction will be more than what we have seen in Marine.
The second reason is that Fishman Island was once part of Mariejois, and the Nobles used that place to harvest fishermen by letting them breed inside that place, then selling them or enslaving them.
Something horrible must have occurred, and the nobles decided to throw them back to the sea with their whole island. As they were merely slaves to them and owned them, they could do anything to them, and as a punishment, they banned them from under the sea.
After hearing this out, Luffy will undoubtedly lose it and end up destroying Fishman Island so that Queen Otohime’s wish will come to fruition, which is that the Fishman people may live happily with the rest of the World on land, travel, and enjoy all the riches the grounds should offer.