A little sea princess, longing to be human, trades her mermaid's tail for legs, hoping to win the love of a prince and earn an immortal soul for herself.

Uncovering an ancient evil, Serafina, a mermaid of the Mediterranean Sea, searches for five other mermaid heroines who are scattered across the six seas, to save their hidden world.

When she incurs Neptune's wrath by finding a diamond ring buried under rocks in the ocean, Emily is put under a curse that will force her to choose to be either a mermaid or a human and split up her parents forever.

"Twelve-year-old Kela is still mourning her mother when she finds a mermaid's comb while she and her friend are looking for sea glass on her Caribbean island; such combs have magic in them, and touching it opens a connection to the mermaid Ophidia who can grant her wish, to bring her mother back to life--but all wishes have consequences, and magic demands a price which may prove to be more painful than the loss of her mother."--

As they search for their missing father near their Cornwall home, Sapphy and her brother Conor learn about their family's connection to the domains of air and of water.

Vacationing in a sleepy beach town for the summer, Sam is pursued by hordes of blonde girls before falling in love with the unusual DeeDee, who compels him to uncover secrets about the community's ocean-dwelling inhabitants.

Assaulted and left on the cliffs outside of her grim Alaskan fishing village by her abusive, alcoholic uncle, fourteen-year-old Luce expects to die when she tumbles into the icy waters below, but when she instead transforms into a mermaid she is faced with struggles and choices she could never have imagined.

Since cutting off her wings to save Never Land, Rani, a water-talent fairy, feels out of place with the fairies and wonders if she should live with the mermaids instead.

Seventeen-year-old Lily, half-mermaid and half-human, has been living on land and attending high school, where she develops a crush on a boy but is afraid to tell him of her true destiny as the ruler of the undersea kingdom of Thalassinia.

Sapphy and her brother Conor have been called to take part in an ancient and dangerous coming-of-age ritual, but Ervys and his followers are determined to stop them.