George decides to take the family on holiday to Costa Rica where he will be filming a whale documentary, while Barbie and friends land summer jobs at a water park in Malibu.

After her boss is fired, Barbie is promoted with new responsibilities. Unfortunately, she learns that one of those responsibilities is that she has to fire Ken. Meanwhile, Skipper and Stacie join Chelsea on a quest to find a missing mermaid, but end up getting lost.

Barbie's friends struggle to adjust to her becoming their boss at Oceans Extreme. In Costa Rica, Stacie, Skipper and Chelsea close in on the missing mermaid.

Barbie and her friends create a plan to stop smugglers and save a baby whale. As a reward, Barbie gets a ticket to Costa Rica, where she joins her family to see the whales arrive.

On her first day back to school, Barbie learns that Golden Beach High's newest student is none other than Tammy, her opponent from the baking competition show.

Barbie offers to help Renee build her school basketball team by trying out, but she soon realizes that she is not as great as she thought she would be.

Ken asks Barbie to help him invite Harriet to a school dance. Despite her mixed feelings, Barbie agrees to do it, because what are friends for?

When Margaret hesitates to take a promotion at her job, Barbie and her sisters work together to prove to their mother that they can handle extra responsibilities.

Barbie tries to help Skipper adjust to high school by inviting her to join her lunch table. When Skipper bonds with her friends, Barbie unexpectedly feels left out.

The Roberts family are driven to enter Malibu's annual Family of the Year contest, competing against the family that has won every year for the past decade: the Reardons.

Barbie and Skipper collaborate on their school community service project at the Water Park, but the two clash when Skipper does not put in an equal amount of effort.

The Roberts host their neighbors at the Dreamhouse when an earthquake causes a power outage. Meanwhile, Barbie and Skipper decide to raise funds for the destroyed library.