One Piece: The Giant Mechanical Soldier of Karakuri Castle

The StrawHat crew salvage a treasure chest from a sinking wreckage during a raging storm, but it turns out to be an old lady hiding inside it. To get the Straw Hat Pirates to take her home, she promises them the treasure of a golden crown on her island, Mecha Island. The island is impossible to get to by Log Pose. So instead they got there by Kame Pose. Which contain a small turtle pointing to the island. When they arrive, the Going Merry was first attacked by the lord of the island: Dr. Rachet. But later he decides to use the pirates to help him solve the riddle of the Golden Crown.