The Undersea Kingdom

 is the seventeenth episode of the second season of Star Teens Unite!.

Summary
While the Star Teens are enjoying a day at the beach, Princess Nemo arrives and asks them to help protect her kingdom from a gigantic octopus controlled by Captain Birgus.

Debuts

 * Coral (Nemo's mother)
 * Maris (Nemo's older sister)

Characters

 * Ella
 * Inidra
 * Sandra
 * Felicia
 * Liza
 * Tanya
 * Sheila
 * Bella
 * Princess Nemo
 * Queen Coral (Nemo's mother)
 * Princess Maris (Nemo's older sister)
 * Gigantic Octopus

Voice Cast

 * Aimee Carrero - Tanya
 * Ariel Winter - Princess Nemo
 * Grey Griffin - Sandra
 * Jessie Flower - Princess Maris
 * Jim Cummings - Gigantic Octopus
 * Jodi Benson - Queen Coral
 * Kari Wahlgren - Ella
 * Kate Micucci - Inidra
 * Kimberly Brooks - Sheila
 * Mark Hamill - Captain Birgus
 * Tara Strong - Felicia
 * Vyvan Pham - Liza

Trivia

 * Nemo's mother Queen Coral and sister Princess Maris debut here.
 * Queen Coral's actor Jodi Benson is best known for providing both the speaking and singing voice of Disney's Princess Ariel in The Little Mermaid and its sequels.
 * Star Teens Say: Riptides and currents