Walkthrough:Kingdom Hearts II/Atlantica

First Visit (Swim This Way)
Like in the first game, and his friends transform in this world. regains his blue dolphin tail, re-obtains his octopus legs and  becomes a turtle again. finds them, though has forgotten how to swim (due to his stasis). The help text will teach you how to swim. Talk to.

A musical is near, and is acting strange. asks you to join in on the musical, which and  agree with. You'll be put on a tutorial round, where you must hit the X button to get a Good or Excellent. You need to have at least one to pass. You can try again if you fail.

After you complete this, you'll be ready to perform Swim This Way. You need to have at least one note to clear this song, and you can get up to five notes. Getting an Excellent grants you a note, while getting a Bad takes away one note. After completing the song, you will be re-introduced to, who asks to try to keep 's mind off of the human world. Later on, finds a statue from a newly-sunken wreck. However, and his friends cannot lift the rock out of the way. You'll then return to the, where the help text tells you that, in order to go further in , you'll need to have the Magnet Spell, which can be obtained as early as after defeating in.

Second Visit (Part of Your World)
After you obtain Magnet, a new chapter will be unlocked in.

After landing, go talk to, and select the second choice. A cutscene will begin.

and his friends have managed to move the statue into the. will then begin to sing "Part of Your World" after relising that she might be in love with a human prince. To clear this song, you need to perform 5 Excellents in a row. Some of the notes require you to press triangle.

After completing the song, offers to help, as that's what he's here for, anyway. Meanwhile, completes the song that  asked for, which is said to help  take her mind off the human world, as well as show her how happy it is to be under the sea. However, when shows the song to,  and , it makes them a little nervious.

To continue on with, you need to have your drive gauget at 5, which will happen after defeating the in.