Red Line

The Red Line is a massive continental mountain range that runs along what would be the Prime Meridian on Earth within the world of One Piece. It divides the Blue Sea into two vast oceans and, together with the Grand Line—which runs perpendicular along what would be the equator—splits the world into four seas: North Blue, East Blue, West Blue, and South Blue. The Red Line is one of the two global phenomena that define the geography of the Blue Planet, making passage between the seas difficult without using unique features like Reverse Mountain or the Calm Belt.