What is grand line?

Grand Line is a fictional location in the manga and anime series, One Piece, created by Eiichiro Oda. It is the most dangerous and challenging sea route in the world of One Piece, and only the most skilled and powerful pirates can navigate it successfully. It is located in the middle of the world, stretching from north to south, and is divided into two halves by the Red Line, a massive mountain range that runs across the world. The Grand Line is notorious for its unpredictable weather conditions, powerful sea monsters, hidden dangers, and the existence of the legendary One Piece treasure. The Grand Line is divided into several sections, including the Paradise half and the New World half. The Paradise half is known for its many islands, seas, and Marine bases, while the New World half is a lawless land of powerful pirates, dangerous creatures, and mysterious islands. The Grand Line is the ultimate destination for all pirates, and the ultimate prize to claim.