Atlantica

Atlantica, based on Disney's twenty-eighth animated feature, The Little Mermaid, is an underwater kingdom featured in all three of the main Kingdom Hearts games. Ruled by King Triton and his powerful magic trident, its inhabitants are mermaids and sea creatures. While here, Donald uses his magic to transform the main characters in order blend into the environment. Sora's legs become a dolphin's tail, Donald's legs become octopus tentacles and Goofy's body becomes that of a sea turtle. In Kingdom Hearts II there is no battling in Atlantica and featured minimal exploration. The main form of gameplay was an interactive rhythm game.

The main city of Atlantica is the only "constructed" area, made of what appears to be coral and other underwater vegetation. King Triton's chamber can be found here. Outside the city is the Undersea Gorge, which is a sort of hub to other areas. Here can be found Ariel's Grotto, a secret place where Princess Ariel stores her human artifacts. Also, a path from here leads to a rotting sunken ship that has become the home to many sea creatures. A more sinister area of the sea can be accessed from here: the Den of Tides and the sea witch Ursula's lair.