Merliah is an excellent swimmer and surfer, and one day she discovers she can breathe underwater. She meets Zuma, a pink dolphin, who tells her that her mother is the mermaid queen of Oceana.
When Merliah travels to Australia for a surfing tournament, a jealous competitor steals her mermaid magic and releases the evil Eris from her prison, and Merliah must save the mermaid kingdom without her mermaid powers.
"Barbie returns as the beautiful fairy Elina...The evil fairy Laverna has kidnapped Mermaidia's Price Nalu! Elina transforms into a mermaid and, with help from her friends Bibble and Nori, sets off on a daring rescue mission..."--Cover back.