After the Lipschitz Cruise leaves the pier leaving the babies and their family behind, Stu calls out to them after the cruise ship leaves entirely. Stu and Spike were both seen in a small ramshackle boat called the S.S. Nancy as Stu planned the family their own trip, much to their disgust.
After leaving the pier, Tommy and the gang seem to be enjoying their time on the Nancy, but the grown ups weren't. Stu invited Chas to make him First Mate, but Drew was furious at Stu and planned for them to get onto the Lipschitz Cruise at the next pier, Drew even takes control of the wheel. Didi tries to call for help on the radio, at first she gets a signal from the Lipschitz Cruise but then she contacts the Thornberrys' Camp on a near by island called Uninhabited, where the Thornberrys were looking for a Clouded Leopard.
Later on, the Nancy went into a storm. As the Nancy went over big waves, a giant tidal wave approaches it. Betty quickly calls out to everyone to get below. The family quickly gets inside the Nancy as the tidal wave splashes down onto the boat, causing it to sink, and then rise back up to the surface. The Nancy pops up back at the surface capsized. Chas grabs the door they opened to get in, but before everyone tells him not to open it, Chas opens the door causing water to flood the inside of the boat.
Charlotte though manages to use her shoe to break a hole in the bottom of the Nancy so the family can escape. The family climbs out, except for Betty who dives down and gets Dil's binky and an inflatable life raft. Betty swims up to the surface and gives Dil back his binky and blows up life raft.
The family abandon ships and the Nancy sinks after they jump into the raft, leaving them lost at sea (before landing on the island the next day).