This is the Sea of the Sky! The Knight of the Sky and Heaven's Gate

Carried skyward on the Knock-Up Stream, the Going Merry tears through the dense clouds, and Luffy, treating the vapor like water, holds his breath as the hull rises. Its wings snap loose the moment the ship pierces the top layer of the White Sea. Down in the Blue Sea, Cricket sits lost in thought as the stream fizzles out, while Teach, adrift on the scraps of his raft, grudgingly admits the crew slipped away and expects the two groups to meet again on the Grand Line. On deck the others marvel at clouds solid enough to hold a ship, until Chopper discovers Usopp has drowned and revives him with CPR. With the Log Pose still tilted nearly upright, it is clear there is farther up to climb.

Ignoring Sanji's caution, Usopp plunges into the cloud ocean and only sinks lower, prompting Robin to conclude the sea has no floor and that he is falling rather than swimming. Luffy stretches an arm down while Robin lines it with eyes via Ojos Fleur to locate him, then extends grasping limbs through Veinte Fleur to haul him up. The pull-back drags along sky creatures, an eel, an octopus, and a wriggling fish, which Zoro, Sanji, and the rest subdue and cook. A masked warrior wielding a heavy shield alongside a bazooka-style cannon then charges the deck, flooring Zoro, Sanji, and Luffy, all drained by the thin air at 7,000 meters. A mounted rider swoops in, knocks the attacker into the sea, and introduces himself as Gan Fall, the Sky Knight, riding his bird Pierre. He hands them a whistle good for one free summons and reveals that Pierre ate the Uma Uma no Mi and can turn into a Pegasus. Steering toward a cloud shaped like a waterfall, the crew at last reaches Heaven's Gate.

This episode opens the Skypiea Arc. It brings in several newcomers, including Wyper, Gan Fall, Pierre, and the gate inspector Amazon, who quotes an impossible toll before summoning the Express Lobster to carry the ship up the waterfall. Robin's Ojos Fleur and Veinte Fleur make their first appearances here, as does the Uma Uma no Mi. Amazon closes the episode by calling on Enel to pass judgment on the seven who entered without permission.