Atlantica

Atlantica is an undersea kingdom that is based on the 1989 film The Little Mermaid, as well as its sequel The Little Mermaid 2: Return to the Sea and its prequel The Little Mermaid: Ariel's Beginning. It is divided into two areas: the sea and the surface. The sea portion is ruled over by the firm but fair King Triton, who oversees his seven daughters in his palace. The surface portion is home to Prince Eric and eventually Ariel after she finds her love for him. Whenever outsiders enter the sea portion, they transform into merfolk (if human) or sea creatures (if animal). On the surface, the outsiders wear clothes befitting the Danish countryside. The Keyhole to Atlantica is inside King Triton's trident.
== Setting ==
=== The Sea ===
The main area in the first game is the Sea, with Return and Dawn expanding upon it. The party starts in the Tranquil Grotto, where the group meets Ariel, Sebastian, Flounder and Aquata. Aquata shows the trio how to swim underwater during this time, as well as attack and use magic. 
== Story ==
=== Kingdom Hearts: Heart of the Keybearer (Under the Sea) ===
Akira, Skye and Harlynn land their Keyblade Gliders in the sea, much to the former's concern before his sister assures him that their outfits have magical properties that transform them as the world sees fit. Meanwhile, a young mermaid princess named Ariel has a nightmare about her mother, Queen Athena, being run over by a pirate ship. Her big sisters are concerned about this, and assure her that it was just a dream (Alana even offers to sleep with her for the night). 
As the Trinity Trio lands in Atlantica, they discover that they have transformed into a new form to fit the world, with Akira and Harlynn being mermen and Skye being a mermaid. This is where they meet Ariel, along with her best friend Flounder, oldest sister Aquata and Sebastian, King Triton's majordomo. Because our heroes don't know how to swim, attack or cast magic underwater, Aquata teaches them to do so. Soon after the underwater mobility lessons, a group of Sea Neons and Screwdivers show up as they take care of them. Ariel then asks them to accompany her and Aquata to the palace, as the latter explains why music is banned from this world: Triton had given Athena a music box, but she was killed while trying to retrieve it. 
As the group arrives in the palace, they meet King Triton, who is aware they are from another world, and Ariel's other sisters: Andrina, Arista, Attina, Adella and Alana. Triton scolds his youngest daughter for staying out past curfew, hence why Aquata came to pick her up, and implores her new friends to protect her from the Heartless at all costs. Just then, the girls' governess Marina Del Rey arrives, informing them that their dinner is ready. Skye senses darkness within Marina, and Triton tells her and her teammates to be careful around her. They then join Ariel and her sisters in eating dinner (as they obtain some new recipes for their cookbook) and helping each sister minus Ariel with an activity pertaining to them, gaining a special present for each one they complete.
After a long evening, it is time for bed as the girls tuck in for the night, as well as assembling beds for their guests. Shortly after they fall asleep, however, Ariel wakes them back up and tells them that she found the music box that Triton gave to Athena, revealing that she and her sisters got confined to the palace because they were going to a secret garden where they could play music. As they quietly leave the palace, Akira hears Marina speaking with someone (who turns out to be Fanha, who has also become a mermaid), learning that Ariel is not one of the Princesses of Heart. This upsets her, who had wanted to steal the princess's heart to open the Door to Darkness like Maleficent asked her to, but she vows to have said heart anyway because of her jealousy. The group then sneaks out of the palace, but unknown to them, Sebastian was following them and so was Marina.
Our heroes soon come to the Sunken Ship where they find the music box after dealing with Glut the shark, and are ready to swim back to the palace to help Triton remember what music was like before his wife died. Meanwhile, at the palace, Marina sneaks into Triton's chamber and steals his mighty trident so she can deal with Ariel. Once they arrive back at the palace, Triton is furious at Marina after he learns she is a black widow who is jealous of his daughter, and the gang has a fight with her. However, after her defeat, Marina succumbs to the darkness in her heart out of jealousy, which transforms her into the Sea Scourge. 
After destroying her Heartless (and gaining the Thundara magic upgrade), Triton starts to sing a song that the music box is playing as he allows music to be played in Atlantica once again, while his trident starts to glow, revealing that it is the world's Keyhole. Akira seals it, and the trio bid Ariel and King Triton goodbye (in a song) as Ariel hands them the Crabclaw Keychain from her collection.
During the end credits, Ariel and her sisters are shown participating in a concert conducted by Sebastian, while King Triton and Flounder enjoy it.
=== Kingdom Hearts: Return of the Keybearer (Part of Your World) ===
Category:Locations