The Aquarathi Books in Order

The Aquarathi is a young adult fantasy series with undersea royalty, human disguise, and a mythology that feels closer to hidden kingdoms and powerful sea creatures than to standard mermaid fiction. It starts with a girl hiding in plain sight, then keeps asking what that girl owes to the world she left behind.

Nerissa Marin is the heart of the series. In Waterfell, she is living on land in human form, trying to stay unnoticed until the day she can reclaim the undersea throne stolen after her father's death. That simple survival plan falls apart fast. Her human life gives her cover, but it also gives her friends, habits, and feelings she cannot easily shut off, especially once love begins to complicate everything.

The bigger series arc is about duty versus desire. Nerissa cares about her people and her crown, but the surface world keeps tugging at her, and so does Lo. In Oceanborn, that tension gets sharper once she is queen and has to choose between protecting her rule and going after the man she loves when he is poisoned. Court unrest and shifting loyalties make the undersea world feel just as dangerous as the land.

Water is everywhere in these books, but safety is not.

SeaMonster adds another angle by shifting attention to Speio, one of Nerissa's protectors. Through his connection with Anya, the series gets a more personal side story while also expanding the emotional reach of the world. It is a useful reminder that Nerissa's choices ripple outward and affect far more than one central romance.

If you like fantasy with hidden royalty, watery worldbuilding, and a heroine torn between two lives, this series has a lot to offer. Start with Waterfell and read straight through for the strongest payoff. The books are driven by action and emotion in pretty equal measure.