Mermaids Shelly and Echo are excited to begin third grade at the prestigious Trident Academy, but snooty Pearl, jokester Rocky, brilliant Kiki, grumpy Mr. Fangtooth, and an argument over their first project challenge the best friends. Includes facts about marine plants and animals and words to the Mermaid Tales Song.

When her class at Trident Academy visits a pod of whales, Kiki Coral must overcome her fears with the help of her friends.

A shark has been spotted in Trident City! Pearl Swamp is so scared, she needs a shark Guard to escort her to and from school. She doesn't trust anyone who likes these terrifying creatures, especially Kiki Coral, who isn't nearly as frightened as Pearl. And to make matters worse, Pearl accuses Kiki of stealing her precious pearl necklace! Will the sharks destroy the peace of their sparking city? Or will the mergirls have to swim in dangerous deep-sea...

While preparing for a unit on storytelling, the mermaids of Trident Academy learn of a legendary pirate treasure in their own city and Pearl decides to find it, despite a warning that it is guarded by a ghost.