It's an ocean theme for Sora and company in volume 3 of Kingdom Hearts! After their ship is swallowed by Monstro, the travellers help Geppetto and Pinocchio fend off some Heartless and escape from inside the giant whale. After that, it's a trip under the sea - to a place that already has its own 'keyblade', which Ursula tells Ariel is her ticket to other worlds. Then, onboard Captain Hook's pirate ship, Sora and Riku have different ideas on what lengths to go to save Kairi. When it comes to dealing with the Heartless, let your conscience be your guide, and don't forget the pixie dust!
