Before leaving the Gummi Ship, Donald uses his magic to change the group into aquatic creatures; Sora into a merman, Goofy into a turtle, and himself into an octopus. Shortly after arrival, Ariel, Sebastian, and Flounder swim to the group's area, fleeing from the Heartless. The trio promptly defeat the Heartless, earning Ariel's attention. She leads the group to the palace, where they meet her father: King Triton. Triton, furious, chastises Ariel for leaving the palace. He also asks why the trio is here. Goofy accidentally blurts out that the group is searching for the Keyhole. Triton immediately claims there is no such thing in Atlantica. King Triton also orders that Ariel is under no permission to leave the palace. Despite her father's orders, Ariel leaves the palace anyways, dragging along Sora, Donald, and Goofy.
With only Sebastian by his side, King Triton vents that perhaps he is too strict with his daughter. Sebastian is instead worried about the Keyhole, learning nothing from King Triton. Triton redirects, asking how great the Heartless's forces are. Sebastian reports that their enemies numbers are increasing every day. Triton grips his trident, stating they shall not do as they please.
Ariel takes the group to her secret grotto, wanting to show her collection of the outside world. They find King Triton inside, as well as the remains of Ariel's collection. Ariel storms away, saddened. Meanwhile, Triton revels that it were the dark creatures that destroyed Ariel's collection. Triton asks the group if they are indeed from another world. After confirmation, Triton concludes that Sora is the Keyblade wielder. The King orders the group to leave his world, claiming the Keybearer shatters peace and brings nothing but ruin.
Meanwhile, Ariel is shown alone, pouting at how her father treats her. Flotsam and Jetsam appear, claiming there is a lady they know who can help Ariel. When asked "who?," Ursula reveals herself.
(Numbers indicate order of appearance.)
Items of note
Kingdom Hearts references