While the continent appears impossible for any boat wishing to cross between the seas or to certain sections of the Grand Line, there are certain pass points at which a ship can cross between the Blues: going up the waterways of Reverse Mountain (typically used to enter the Grand Line by pirates), gaining government permission from the holy government land of Mariejois, or submerging into Fishman Island, which is placed around a hole that links directly between Paradise and the New World.
The Red Line is like a group of islands connected together. The Red Line that crosses the Grand Line has its own Summer, Winter, Spring and Fall "islands". The Red Line bears the world capital, Mariejois, and is said to be 10,000 meters deep from ocean level to Fishman Island. At the same time, it is high enough above sea level to be considered impassable, and is indestructible, meaning that it is almost impossible to pass over it or under it without using either of the entrances. Fisher Tiger, however, managed to climb up the entire Red Line with his bare hands to attack Mariejois. The whole of Germa 66 was also able to climb over the Red Line, from North Blue into East Blue, using its amphibious ships.
- ↑ One Piece Manga — Vol. 62 Chapter 604, Nami explains the islands that form the Red Line.
- ↑ One Piece Manga and Anime — Vol. 51 Chapter 496 and Episode 390, Hachi explains the height of the Red Line.
- ↑ One Piece Manga and Anime — Vol. 12 Chapter 104 and Episode 63, Laboon ramming the Red Line in futility.
- ↑ One Piece Manga and Anime — Vol. 53 Chapter 521 and Episode 415, Boa Hancock talks about Fisher Tiger.
- ↑ One Piece Manga — Vol. 84 Chapter 841, Germa 66 is shown crossing the Red Line.