The Grand Line and where piracy origanted from and the fact that "The Pirate King" Gold D.Roger  moments before his execution revealed that his Ultimate treasure One Piece is hidden somewhere on the world only raised the popularity of piracy by an extreme amount


The Grand Line is mostly a very large ocean which is why the first pirates used ships to sail this great sea.It is separated into 4 pieces east blue,west blue,south blue,and north blue.Islands are scatters all over the world and there are rare Islands that are as big as a nation and have completely different enviroment than the rest of the grand line.


The grand line's logic differs from other world's in a few aspects.One of them are the popular devil fruit strange fruits and if someone devours one of them they gain a variety of supernatural abilities.Another difference in logic is a force called Haki in the Grand Line will power can be manifested into energy that affected the body phsiycally and mentally.