Episode of Merry

Episode of Merry: The Tale of One More Friend is a TV Special of the One Piece anime. It aired after Episode 608.

The special chronicles the Straw Hat Crew's first ship Going Merry recreated with brand-new animation. Telling an abridged version of the Water 7 and  Enies Lobby arcs from Luffy and Usopp's fight and Robin's disappearance to the crew's battle against CP9 to get Robin back and the crew's final farewell to the ship.

Short Summary
During a lull in their travel, the Straw Hats are milling around the Thousand Sunny. Usopp, Chopper, and Brook head out to explore the surrounding ocean in the Mini Merry II. Brook asks about the Merry, since he joined after the crew had acquired the Sunny, and Usopp and Chopper tell him about their old ship, from her journey from Syrup Village to the events leading up to her end during the Water 7 and Enies Lobby arcs.

Trivia

 * The special is apparently meant to take place before One Piece Film Z (specifically Glorious Island) as the crew are in their outfits from the start of that movie. Considering Nami is still wearing her dress from the Z's Ambition Arc, it likewise is set some time after that arc.
 * Events that were not canon were animated during the flashback including bits from the Warship Island Arc and the G-8 Arc.
 * Brand New World and Memories were used within the special.
 * A Klabautermann is seen on the Sunny.