A kingdom submerged / Deborah Grace White

"A determined mermaid, the powerless son of a magic-wielding line... two worlds never meant to collide In spite of being a nameless orphan, Merletta is determined to win the prestigious rank of record holder. And she has no intention of letting a little thing like universal disdain stop her. Lord Heath knows nothing of mermaids, but coming from the noble House of Dragonfriend, he's no stranger to magic. Except, in spite of having a dragon for a best friend, Heath is the only magic-less member of his family. Not that he covets the power around him. All he wants its to defuse the growing tension between the power-wielders and their royal cousins. These two worlds couldn't be further removed... until Heath's search for solutions takes him to the forgotten island of Vazula. Now the kingdoms of both land and sea are set on a new current, one which will carry both Heath and Merletta beyond the limit of everything they thought they knew. Because with someone underwater trying to do much worse than push Merletta from the program, and someone on land targeting Heath's family, the insurmountable barriers keeping Heath and Merletta apart might just be the least of their problems." -- Author website.