King Triton and his wife, Queen Athena, rule over the underwater kingdom of Atlantica, which is filled with music and laughter. They have seven young daughters, the youngest of whom is Ariel. The merfolk are shown relaxing in a lagoon above water, and Triton gives Athena a music box. Suddenly, a big pirate ship approaches. Everyone escapes except Athena, who is crushed by the ship when she tries to save the music box, due to the pirates having apparently lost control of their own vessel and unable to divert it away from crushing Athena and running aground. Devastated by Athena's death, Triton throws the music box into the ocean and bans music from the kingdom.
Ten years later, Ariel and her six older sisters are not happy with living under a strict routine maintained by their governess, Marina Del Rey and her assistant, Benjamin. Marina hates being the girls' governess and longs to be Triton's attaché, a job currently filled by Sebastian the crab. Ariel hates their current lifestyle, which brings her into conflict with her father. One day, Ariel encounters Flounder the tropical fish whom she later follows to an underground music club. She is overjoyed by the presence of music and is shocked when she sees Sebastian performing there. When her presence is revealed, the entire band stops playing and hides, believing Ariel will tell her father about them. Ariel sings a song explaining her love of music and the remembrance of her mother and she joins the club with an oath.
Ariel returns to the palace, and her sisters confront her over her disappearance. She explains where she was, and the following night all seven girls go to the club to have fun. Marina secretly finds them, and she later reports their activities to Triton. Sebastian, Flounder, and the band are sent to jail, while Marina gets the job she wants.
Triton confines his daughters to the palace and Ariel says that her mother would not have wanted music forbidden. She swims to the bedroom, with her sisters following and telling her that no one is happy except Marina. Marina, who is not the girls' governess anymore, is now Triton's new attaché and is happy with her new job, while everyone is sad and miserable. That night, Ariel leaves Atlantica and frees her friends. Sebastian leads them to a deserted place away from the palace where Ariel finds Athena's music box, as Sebastian hoped.
In the kingdom, Marina happily talks to Triton about her new job but is interrupted by Attina, the eldest of Ariel's six older sisters, telling Triton that Ariel is not in Atlantica. Triton orders his guards to bring Ariel back home, ignoring and angering Marina. In her lair, Marina tells Benjamin that she releases her electric eels from the dungeon to kill Sebastian and Ariel so she can remain as Triton's attache. Ariel, Flounder and Sebastian decide to return to Atlantica to bring the music box to Triton, hoping that it will change his mind, as he has forgotten how to be happy after Athena's death.
On the way back, Marina and her electric eels confront Ariel, Flounder, and Sebastian. Before music is restored back into the kingdom, the final battle begins when Marina bans Ariel from going back to Atlantica. Marina wants to stop them so she will retain her position of "power", and a struggle ensues. The music band friends save Ariel and Flounder from being murdered by Marina's three electric pet eels. It ends when Marina almost kills Sebastian, but Ariel pushes her away, getting hit in the process. Triton arrives in time to witness this, and he is remorseful for his actions. He sings the lyrics of "Athena's Song", and Ariel wakes up. Triton apologizes to Ariel for not listening to her and for not answering and sends her back to Atlantica before ordering his guards to arrest Marina.
The film ends when Triton allows both love and music back into his kingdom and appoints Sebastian as the new court composer of Atlantica, much to everyone's glee with Ariel and Flounder. Everyone, including Ariel, Sebastian, Flounder, and six older sisters, rejoices except Marina, who has been sent to prison and is constantly blowing her nose.
A teaser trailer and musical preview of the film (an alternate version of "Jump in the Line") were attached to the Platinum Edition DVD of The Little Mermaid, which was released in July 2005. At the time, the working title The Little Mermaid III was still being used. At that point, the preview showed Eric's ship blowing up in a storm, Melody's necklace falling under the water, and Ariel's face silhouetted in the water. This was probably based on a previous version of the story since the trailer doesn't really match what actually happens in the released movie. In addition, a storyboarded sequence developed by Tod Carter indicated that the film was initially intended to be a sequel of at least The Little Mermaid, if not Return to the Sea, with part of its plotline involving locating a white whale at the behest of Prince Eric.
- Jodi Benson as Ariel
- Sally Field as Marina Del Rey
- Samuel E. Wright as Sebastian
- Jim Cummings as King Triton/Shelbow
- Parker Goris as Flounder
- Kari Wahlgren as Attina
- Jennifer Hale as Alana
- Grey DeLisle as Aquata/Arista
- Tara Strong as Adella/Andrina
- Jeff Bennett as Benjamin
- Lorelei Hill Butters as Queen Athena (speaking voice)
- Andrea Robinson as Queen Athena (singing voice)
- Rob Paulsen as Ink Spot/Swifty/Additional Voices
- Kevin Michael Richardson as Cheeks/Ray-Ray
The score to the film was composed by James Dooley, recorded the score with a 72-piece ensemble of the Hollywood Studio Symphony, as well as a big band, at the Sony Scoring Stage The film features new songs written by Jeanine Tesori, along with covers of previously-recorded calypso songs that were arranged by Dooley. The songs featured in the film are:
- Athena's Song/ Endless Sky - Performed by Andrea Robinson (Queen Athena)
- Just One Mistake - Performed by Sally Field (Marina Del Rey)
- I Remember - Performed by Jodi Benson (Ariel)
- Jump in the Line (Shake, Shake, Shake, Senora) - Performed by Samuel E. Wright (Sebastian) and chorus
- Jump In The Line (Shake, Shake, Shake, Senora) A cappella version - Performed by Parker Goris (Flounder), Samuel E. Wright (Sebastian), Jodi Benson (Ariel) and chorus
- Man Smart, Woman Smarter (instrumental only)
- Just One Mistake (reprise) - Performed by Sally Field (Marina Del Rey)
- I Will Sing - Performed by Jeannette Bayardelle
- It is currently unknown if a soundtrack album will be released.
The film was released on Region 1 DVD in the USA on August 26, 2008, and on Region 2 DVD in the UK and Europe on September 22, 2008. The DVD contains special features including deleted scenes, a production featurette hosted by the director, games and activities, and a featurette hosted by Sierra Boggess about the Broadway musical.
On December 16, 2008, the film was released in a "The Little Mermaid Trilogy" boxed set that includes The Little Mermaid (Platinum Edition) and The Little Mermaid II: Return to the Sea.
On November 19, 2013, the film was released on Blu-ray in a 2-Movie Collection with The Little Mermaid II: Return to the Sea.
The DVD became the top-selling DVD for the week ending April 30. Reviews of the film from audiences were mixed, though the film received negative reviews from critics. The new villain, Marina Del Rey, has been criticized as being a poor follow-up to Ursula. The animation quality of the film has been praised as being "impressive" for a direct-to-video and comparable to that of the original film. A mildly negative review has described that in the film "goofiness often gets buried too often underneath a blah story that's much too run-of-the-mill to allow the emotional oomph of the characters' plights to truly impact" The music has also been criticized as being unmemorable, with one review stating that "to label this a musical would be false advertising". The movie received a 33% Rotten rating on Rotten Tomatoes.
- There were some continuity problems between the TV series, this movie, as well as the first film.
- One notable issue is how Flounder and Ariel met. The TV series shows that they met when Ariel was still a child, while this film shows Ariel to have been older.
- Marina Del Rey, Triton's governess, was seen surfacing (as well as being almost humiliated by Scuttle) while celebrating her victory, something that would not have been possible had there been a ban on visiting the surface, especially of someone with as high of a position of power as Marina.
- Another major plothole, was in the ending. The original film implied during "Daughters of Triton" that the concert that Ariel missed was supposed to be her debut appearance in the band, and that her sisters had been veterans in the band. This is something that would not have been possible seeing how Ariel had saved music in Atlantica, which would have made her band leader instead of waiting a year to join.
- On a related note, the birth-order of Ariel's sisters were changed; from both the TV series and the original film (the latter being strongly implied from the lyrics of the song "Daughters of Triton" had their birth order as Aquata, Andrina, Arista, Attina, Adella, Alana, and Ariel.
- Jim Cummings voices King Triton in this film due to Kenneth Mars being unable to show up for the recording due to his illness. Four years later, Mars passed away from pancreatic cancer on February 12, 2011, at the age of 75.
- Before details of the plot were revealed, some fans thought that the premise was going to be about Ariel telling Melody about her origins, which was backed up by Tara Strong being credited as a Voice Actress involved in the film, as well as a leaked storyboard where Ariel is conversing with Sebastian and Eric comes in and asks if someone's acting a bit crabby, and also the teaser trailer in The Little Mermaid Platinum Edition.
- It was originally planned to make Ariel more "contemporary" during the development of the prequel. However, Jodi Benson fought to have Ariel retain her characteristic rebelliousness.
- This is the last sequel to a movie from the Disney Animated Canon until Ralph Breaks the Internet in 2018.
- ↑ https://web.archive.org/web/20070315222827/http://www.todcarter.com/gallery/gallery_images/mermaid_1.jpg
- ↑ And then there's the youngest in her musical debut Our seventh little sister, we're presenting her to you to sing a song that Sebastian wrote.