Sanji wants a sea where every ocean’s fish can share the same water. Luffy keeps making enemies of the people who sit above everyone else. The old Red Line theory gives those two journeys a spectacular meeting point: the world’s biggest wall comes down, and the cook’s impossible sea becomes possible.
The theory: the All Blue needs a different map
The claim is that destroying part of the Red Line will help create or restore the All Blue, with Luffy’s final struggle opening the seas that divide Sanji’s dream. Fish-Man Island’s future may be bound up in that upheaval, but neither the demolition nor its connection to the All Blue is confirmed.
The appeal is that Sanji’s destination could depend on changing the barriers the crew has spent the voyage crossing. Finding the treasure and opening the seas would then become connected goals. The evidence still has to join those two ideas.
Why the clues fit together
Start with the actual dream. The flashback beginning in chapter 56 introduces the All Blue as a legendary sea containing fish from the world’s different oceans. (The linked chapter script is an unofficial Spanish translation.) That gives us a concrete test: a spectacular stretch of water alone will not do. Its marine life has to cross the boundaries we know.
Those boundaries are a major part of the adventure. Chapter 101 establishes both Reverse Mountain’s converging currents and the Calm Belt’s hazards. Much later, chapter 496 lays out the miserable choice at the other Red Line crossing: seek government permission to pass through Mary Geoise and leave your ship behind, or take the dangerous underwater route through Fish-Man Island.
The wall is therefore both a physical obstacle and a place where power controls movement. Artur’s recent geopolitics discussion, especially its opening explanation of the separated seas, is a useful lens here: distance and difficult crossings help keep communities apart. My inference is that opening those routes would give the final victory consequences ordinary people could actually use.
Then comes the warning under the wall. In chapter 610, Shyarly predicts Fish-Man Island’s destruction and identifies Luffy as responsible. The manga’s vision shows a straw-hatted figure; the prediction does not explain the motive or mechanism. Since the island lies beneath Mary Geoise, readers can reasonably connect its destruction to a catastrophe at the Red Line. Reasonably is doing work there. Shyarly does not predict an All Blue.
There is also a possible way for the people to survive. Chapter 621 connects Otohime’s campaign to life on the surface. In chapter 647, Shirahoshi’s Sea Kings stop Noah from crushing the island. Chapter 649 links the ark’s preservation to Joy Boy’s unfulfilled promise and identifies Shirahoshi as Poseidon.
That combination makes an eventual evacuation plausible. It does not establish that Noah exists specifically to rescue everyone from Luffy breaking the Red Line. Neptune does not know the full details of Joy Boy’s promise. The theory supplies that missing connection.
Egghead makes the map matter more
The strongest later development is chapter 1115. Vegapunk says the Void Century’s war raised sea levels by 200 meters, submerging the old continents, and attributes that catastrophe to the Ancient Weapons. Our Egghead recap follows the broadcast’s wider fallout.
The important change is that the present map has a history. Its scattered islands are the survivors of a disaster, rather than the only arrangement the world has ever known.
That strengthens the broad idea of another geographical transformation ending the story. It does not prove the Red Line was artificially built, that removing it lowers the sea, or that every change caused by an Ancient Weapon can be neatly reversed. Vegapunk’s revelation opens the question; it does not provide the engineering diagram.
Where the theory still struggles
One hole is not automatically four oceans united. Reverse Mountain already brings currents from all four Blues together without being identified as Sanji’s destination. The Calm Belts also complicate the picture. A breach beneath Mary Geoise might connect routes through the Grand Line, but the story still needs to explain how fish from every Blue reach a common habitat.
There is a second problem: a legend usually describes something people believe already exists. The All Blue could be a hidden sea waiting to be found. A restored ancient sea could reconcile that legend with a changed future map, but that is another assumption, not evidence.
Finally, destroying a home demands more than a beautiful symbol. Luffy would need to protect its residents, and they would need a future they choose. Noah and Shirahoshi make rescue imaginable; a giant ark does not settle displacement, safety or equality.
Verdict: persuasive destination, uncertain mechanism
I lean toward a major opening of the seas helping fulfil Sanji’s dream. The Red Line version remains plausible because it ties a specific obstacle to a specific prophecy and leaves room for Shirahoshi’s long-awaited role.
The decisive clue would be a direct link between the All Blue’s marine life and the world’s barriers, or an explanation of Joy Boy’s promise that requires those barriers to change. Until then, the prophecy supports an upheaval around Fish-Man Island; the missing evidence is that this upheaval would create the habitat Sanji describes.
Spoilers through chapter 1196.
