Use or the keys to move, jump, and swim, while tapping attacks, though the controls are completely customiseable from the pause menu.
You begin the game as the ship's captain, determined to rescue the other people, presumably because 'lost all crew and passengers in an alternate dimension' doesn't look real good on a resume, and you're going to need to get your hands dirty to do it.
I'm not big on large bodies of water at the best of times, but even in my most dramatic moments (of which there are many), when I think of things that could go wrong on a cruise, 'Entire ship and passengers getting sucked into an alternate dimension by vengeful frozen desserts' somehow never made the list, and yet that's exactly what's befallen everyone in Flipline Studios' action-packed platformer Papa Louie 3: When Sundaes Attack.