When the pearls powering Mertropia start to fade, Princess Merlinda must break the rules and swim beyond her mermaid home to save her father's life force.

Nerissa and Sasha look for Merlinda on land. But with her communication bracelet broken, the princess will have to trust her new human friends.

Celia and Tyler help Merlinda, Nerissa and Sasha adjust to their new school above the surface and try to find answers about their missing map.

A whale rescue leads Merlinda and her friends further on their quest to find more pearls — but danger is waiting below the surface.

A day at the amusement park proves relaxing — and perilous — when the gang's greatest threat makes an appearance. Alex sets out on his own mission.

While Merlinda, Nerissa and Sasha use their powers to help Tyler and Celia save the rescue center, Barbarossa and Tempesta concoct a plan of their own.

The group continues their search for the missing pearls inside a dormant volcano. But Barbarossa is waiting in the shadows to disrupt their plans.

As Merlinda, Nerissa, Sasha and Alex make their way back to Mertropia, they discover that an unwelcome force has entered through the portal.

An old foe becomes a friend as Merlinda returns to Pirate Cove to try and save Nerissa, Alex and the pearls. Fred learns the truth about his father.

With a newfound confidence, Merlinda is ready to defeat Barbarossa once and for all. Will she be able to save her friends — and Mertropia?