Currently, the anime is divided into roughly 10 major sagas.
If you are looking for specific milestones, here is a condensed roadmap: one piece episode list
Note: Episodes 326–336 are recap/special episodes. Currently, the anime is divided into roughly 10 major sagas
Because One Piece is a weekly anime that often catches up to the manga, the studio produces "Filler Arcs"—original stories not written by the creator, Eiichiro Oda. one piece episode list