The episode begins as we see Courage, Muriel and Eustace sitting in the bleachers at Wet World, watching Jojo the Dolphin perform in his tank. However, Eustace is unimpressed by the Dolphin's tricks and challenges the creature to a swimming race. The farmer fails miserably at doing so, which causes Eustace to set up a rematch for tomorrow and if Eustace loses, Muriel must pack her things and become Jojo's sidekick, much to Courage's chagrin.
At the house, Courage and Muriel begin training Eustace to become a professional-level swimmer. When all fails, Courage disguises himself as a therapist. He then proceeds to hypnotize Eustace, telling him to break out of his hard outer shell and become a new self and a better swimmer. It works, and Eustace, Courage and Muriel go to Wet World for the rematch. Courage becomes terrified when he realizes Eustace must beat Jojo in a treacherous obstacle course.
Eustace and Jojo start the swimming race and the farmer seems to be keeping up with the agile dolphin. Though, Jojo's trainer cheats, by bashing Eustace with a bucket when he leaps up to a high platform. Eustace returns to his old self, calling himself a failure and giving up. Hurriedly and horrified, Courage runs to the side of the tank and tries to hypnotize Eustace again, but instead, it hypnotizes Jojo and his trainer. Jojo's body explodes, revealing a tiny, puny fish. The trainer's body begins to explode, as a small, green lizard hops out. The small goldfish tries to beat Eustace but is ultimately defeated, due to his small stature. Eustace becomes victorious, wining the race.
Eustace is then shown within the farmhouse, swimming in a large tank that is placed in the middle of the living room. Eustace is looking for someone to race, but since nobody wants to race him, he begins to hit the glass of his tank, breaking it and releasing water everywhere, ending the episode.
- Bearded Man
- Duck (Is used to start race)
- Le Quack
- Parachute Lady
- Rich Guy
- Shirley the Medium
- Space Chicken
- First appearance of Jojo and his trainer.
- Other characters that made a cameo in Wet World are Kitty, Conway, Di Lung, Evil Empress, Seagull, Parachute Lady, Elephant, Rumpelstiltskin, Giraffe, Waitress, Bearded Man, Rich Guy, Shirley the Medium, Space Chicken, Floyd, and Le Quack.
- Jojo's "inner-self" was a fish and the Trainer's was a lizard.
- "Sloop John B" by The Beach Boys can be heard at 4:13.
- This and Farmer-Hunter Farmer Hunted are the only episodes in which Eustace is portrayed as the main protagonist. Interestingly neither title refers to Eustace by name.
- Despite dolphins being mammals, Eustace repeatedly refers to Jojo as "a stinking fish" throughout the episode. This is ironic considering that Jojo's "inner-self" is a fish.
- Evil Empress makes an appearance, despite the fact that she was apparently vanquished in the previous episode.