On the way to Hearthome City, Ash and his friends spot a sightseeing steamboat and decide to take a ride. But the old man in charge of the boat informs them that it doesn't depart until noon, which leaves our three Trainers with plenty of time to go shop at a nearby Poké Mart. All their Pokémon stay on the boat to have some fun in the meantime, since there are no other passengers yet. The fun starts to get a little messy, however, and on top of that, Pachirisu's clowning around accidentally sets the ship in motion!
Team Rocket is already onboard and in disguise, planning to carry out their latest criminal scheme. Using the power of song and dance, they lure Pikachu and the Pokémon into a trap—except all the Pokémon escape when the ship suddenly changes course! Pachirisu is still up in the boat's cockpit, and it accidentally turned the steering wheel. Pikachu and friends have no problem blasting Team Rocket off and overboard, but now the boat's new course is taking it right toward a giant waterfall!
Ash, Dawn, and Brock return to the boat dock and discover that their Pokémon are in danger. With the help of the old man's Mantine, Ash and Dawn catch up to the runaway boat and jump onboard. Then, with Ash at the wheel and some Pokémon teamwork, the ship is steered away from the waterfall and back to safety. Our heroes apologize to the old man for all the trouble, but he's proud of what they accomplished and wishes them good luck on their adventures.
Ash and his friends stand on a cliff overlooking a large river. After spotting a large Wailord-shaped boat docked in a harbor below, Brock reads from his guidebook that it will get them to Hearthome City, their next destination. While an old man, supposed to be watching the ship, naps in a chair on the shore, Ash's group boards the ship. They marvel at a large dining room complete with a bandstand and instruments. Pikachu leads everyone up to the sun deck, where they admire the magnificent view. Ash and friends follow and release their Pokémon to join them. The Pokémon take to a game of ring toss while others decide to relax.
Dawn spots the old man napping, and she calls out to him, which wake him up. The old man informs Dawn and her friends that the steamboat leaves port at noon. With plenty of time to spare, Brock decides to stock on supplies. The old man points the group to a Poké Mart nearby. Ash and Dawn also want to do some shopping, though Brock reminds them that someone needs to look after the Pokémon. With the old man’s assurances, Ash and Dawn put Pikachu and Piplup in charge of the other Pokémon while they leave to do shopping. Flying overhead in their balloon, Team Rocket spots the group’s abandoned Pokémon and decide to nab them all for Giovanni.
Aboard the steamboat, the Pokémon have migrated to the dining room. Croagunk settles himself in front of a mirror, staring at his own reflection. Sudowoodo bangs on the piano, Pikachu plucks the bass, Buizel plays the saxophone, and Turtwig plays the drums. Piplup, Pachirisu, Buneary, Aipom, and Happiny enter a dressing room filled with costumes, and the latter three dive into a rack of dresses. Pachirisu looks up on a shelf and sees some balloons, and it imagines itself floating along with Staravia. It rushes up a ladder, ties the balloons around its waist and begins to drift out of the room and into the kitchen. The sounds of crashing pots and pans alerts Pikachu, who narrowly spots Pachirisu floating through. Pachirisu continues onto the bridge, and its balloon pop as it hits the windscreen. Pachirisu is startled by the popping that it lets out an electric shock before fainting unconscious. The jolt starts the ship’s engine, and it leaves the harbor, while the old man is still asleep on shore and completely unaware of the situation.
Meanwhile, Team Rocket take to the stage, with Jessie disguised as the lead while James is dressed as Plusle, and Meowth is dressed as Minun. The three chant a variation of their motto, and the Pokémon dance along with them after being invited to do so. James leads the Pokémon into a small doorway that reads "Welcome," and a door shuts behind them. James waves the key and Jessie and Meowth comment, not noticing Croagunk still at the mirror. Pachirisu, still in the control room, wakes up and falls on the steering wheel, making it turn several rotations. The ship makes a hard turn, and the key falls out of James's hands and bounces across the floor. Team Rocket chases after it, and Meowth picks it up, but they turn around to see the Pokémon have escaped from behind the door and are angry. Aipom uses Swift, Buizel launches a SonicBoom, Piplup uses Bubble Beam, and Pikachu uses Thunderbolt to send Team Rocket flying off the ship.
The Pokémon on the ship look up through the hole created by Team Rocket and see the ship is moving quickly, so they run on deck. Back on land, the old man wakes up and sees the ship chugging away. Ash and friends return and immediately notice the situation, and they ask if they can use one of the other boats to chase after the ship. The man says they aren't fast enough, so he sends out his Mantine, and Ash and Dawn jump on its back and rush after the ship, which is approaching a massive waterfall. The Pokémon on deck are frightened and appear helpless. Pikachu and Piplup nod at each other and attempt to organize the Pokémon. Pachirisu and Happiny get on Staravia's back, while Buneary, Piplup, Aipom, Turtwig, Buizel, and Sudowoodo jump up on the ship's ledge to attempt to stop the impact with attacks. Croagunk is still in front of the mirror, so Pikachu drags him away to help. Ash and Dawn appear alongside the ship, and the Pokémon rush over to meet them.
Ash tells Mantine to jump over the ship, and he and Dawn jump on deck as it does. Dawn admires Aipom and Buneary's dresses, and Ash runs to grab the steering wheel. Dawn tells Piplup to use Whirlpool, which, in conjunction with Ash's turning, causes the ship to turn around. The whirlpool, however, begins to drag the ship back, so Buneary uses Ice Beam to seal it. Ahead is a rock pillar, so Pikachu, Turtwig, and Buizel aim their attacks to break it up. A chunk of rock flies toward the ship, but Mantine crashes through it at the last second, breaking it into pieces that fall into the water. Ash collapses on the wheel in relief as the Pokémon cheer.
Back at the harbor, the old man apologizes, but the group doesn't make a big deal over it because everything turned out okay. In turn, they thank him for the use of his Mantine. The man praises Pikachu and Piplup's quick thinking. As the ship is about to set off, the man wishes the group all the best with their ventures, and he waves as they sail towards Hearthome.