One Piece Episode 66

Episode 66 adapts chapters 110–112.

A Serious Fight! Luffy vs. Zoro: the Baffling Duel! · Whisky Peak arc

Anime

Episode 66A Serious Fight! Luffy vs. Zoro: the Baffling Duel!

Manga chapters

Chapter 110
Chapter 111
Chapter 112

One Pace

The Trials of Koby-MeppoCovers chapters 83–119
The Secret Criminal OrganizationCovers chapters 110–114

The details

Episode 66 adapts chapters 110–112. Adapting several chapters into one episode is why the anime slowly gains on the manga in raw numbers even while falling further behind in story.