The Grandline is a large stretch of sea that wraps around the entire world, bordered on either side by the Calm Belt and at each end by the Red Line.
Overview[]
The Grandline is a massive sea that stretches from North-East to South-West perpendicular to the Red Line and is known as the most dangerous stretch of ocean in the world, often referred to as the Pirates Graveyard (海賊の墓場, Kaizoku no Hakaba).
This massive stretch of sea is what divides the North Blue from the West Blue and the East Blue from the South Blue. The Grandline itself being cut in two by the Red Line which divides the Grandline into two sections known as Paradise and the New World.
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Unlike the Four Blues, the Grand Line cannot be Navigated through traditional means as each island within the Grand Line has its own magnetic field that renders regular compass' useless. As such, the use of a Log Pose is required for navigation of the Grand Line, a tool with the ability to lock onto the magnetic signatures of islands located on the Grand Line.
There are seven known routes that can be taken through the first half of the Grand Line all converging on the Sabaody Archipelago.
After which, the only two entrances into the New World for those traveling through Paradise is to pass through Mary Geoise above, used by traders, merchants, and other legal travelers. Or Fishman Island below, the only option for Pirates and Criminals alike.