The underwater kingdom in Disney’s 2023 film The Little Mermaid is called Atlantica.
Atlantica is the realm ruled by King Triton, Ariel’s father. The kingdom provides the primary underwater setting for the film’s opening sections, including Ariel’s encounters with her family, Sebastian, and the wider sea community.
The name comes from Disney’s established mythology for The Little Mermaid and is also associated with the 1989 animated film. It is not the name of the human kingdom visited by Ariel later in the story.
Viewers sometimes confuse Atlantica with kingdoms from other Disney films. Arendelle belongs to Frozen, Corona belongs to Tangled, and Agrabah belongs to Aladdin. Those settings are unrelated to Ariel’s underwater home.