Hermes gets a mandatory fishing license, and it's valid. The crew heads to the center of the Atlantic Ocean, where they try to fish. Bender uses Hermes' Manwich on Amy's umbrella, tossing it out to sea. When they are about to leave, a giant fish called the colossal-mouth bass causes their ship to sink.
Zoidberg, Bender, and Fry go out looking for food; Fry spots a mermaid. No one believes him, because they think he has "ocean madness". Later that night, the mermaid, Umbriel, looks in Fry's window, and he goes outside. She gives him a breather, making him able to talk to her. She takes him to where the water gets warmer. The next morning, the crew goes out looking for him, and they find out that she has taken him to the famed lost city of Atlanta, where they encounter Merfolk, where they watch a documentary about Atlanta had gotten sunk. The Coca-Cola bottling plant speeded up the process of becoming mermaids.
The crew leaves later except Fry, who has everything he wants. Later that night, Fry finds out that he cannot have sex with Umbriel, because she can only reproduce like fish. Fry runs to catch his friends, just in time to catch Bender's hook. The colossal-mouth bass returns and eats him whole. That day, Bender receives a check for a thousand dollars for his prize catch, until Fry had gotten spit out, and Bender gets mad and tries to choke Fry.