A very loud and crude family wins a free cruise in a package of hot dogs. The eldest daughter falls for Jim after he saves her husband from drowning, while her half-sister prepares to give birth to triplets. The ship's janitor looks to romance a nurse, unaware that she plans to become a nun. An older couple tries to help newlyweds work through their problems, but ends up exposing flaws in its own marriage.

Jim's first cruise at the helm of the Sun Princess is complicated when his ex-wife orders him to take custody of their troubled fifteen-year-old son, Danny. Jim's military discipline clashes with the laid-back style of the other crewmembers, who also object to being forced to baby-sit Danny. Danny vanishes after an argument with his father, and Camille catches him smoking pot. A jilted groom stays in the honeymoon suite with his best man. After they are mistaken for a gay couple, the man (unaware that his friend really is gay) decides to take advantage of the confusion to meet women. A passenger proposes to a woman the day of their first meeting. A woman takes offense when her comedian boyfriend puts down marriage in his act.

Jim's ex-wife comes aboard to celebrate Danny's 16th birthday, then decides that she wants to bring their son home. Will, Camille, John and Suzanne are offered transfers to a better ship. Paolo is furious when his father--a nearly crippled race car driver--comes to visit him. Paolo believes that his father abandoned the family, but Jim learns the truth from Mr. Kaire. A couple meets through a singles activity group, but both parties are hiding secrets about their physical appearance.

Danny hooks up with a teenage girl, only to learn that Jim and her mother were high school sweethearts. The teens are repulsed when their parents rekindle their romance. A couple who fell in love while playing Scrabble online meets for the first time as the ship hosts a tournament. The woman's considerable height advantage proves to be a problem. A congressman tries to win back his estranged wife, while Camille goes all out to impress his fitness-loving bodyguard. Will is annoyed when the cruise line assigns him a goofy assistant, Donald Griswald.

The female passengers complain that Jim will not dance with them. He refuses to admit that he cannot dance, then secretly takes lessons from Camille. Paolo considers giving up his career to marry the older woman he has been dating. Danny is assigned to kitchen duty. He learns that the temperamental chef has a crush on Suzanne and decides to play a practical joke on him. John tries to improve his bedside manner around young patients. Two friends take the cruise in the hopes of finding mates for one another, but end up seeking solace in each other's arms.

Will finds romance with a famous singer who is travelling incognito. Jim assigns Danny to photo lab duty after catching him taking inappropriate photos of women. Danny spots Will with his new love, and ponders whether to respect his friend's privacy or sell the pictures to a tabloid. A twice-divorced couple tries desperately to avoid one another while sharing the cruise with brainless new mates. Engaged virgin anthropologists hope to sleep with other people to gain experience before their marriage. They set their sights on John and Suzanne.