The Sea of Zemira by D.L. Blade

Amidst massive waves, sea monsters, and dragons, arises a bond that cannot be broken⁠—the love between sworn enemies.

In the heart of the land of Zemira lives a king—a wicked king who hates magic.
Using the enchanted crystal he proudly wears upon his crown, he bounds magic to become a mere fairytale, for it threatens his throne. However, such power comes with a price. Not all fall under the crystal’s spell.
Those brave enough to gather in rebellion, with the help from Elven spies, form a resistance. Enraged, the evil king pledges to rid his kingdom of traitors and commits genocide, snuffing out the rebels of land and sea. Yet only two make it out of the waters alive—a siren baby and the fisherman who finds her and raises her as human.
Twenty years after training with her adoptive father, Nola has a set purpose. She will sail to the Fae Kingdom and recruit the Elven warriors to overthrow the king, who once destroyed everything she knew⁠. But she must find her way East soon—their land is dying, and if she fails to bring back magic, Zemira will cease to exist.
Nola never learned to use her tail⁠, so she takes the chance by stowing away on a pirate ship, sailing eastbound. But when she is caught hiding below deck, her presence is not entirely welcomed by the handsome Captain Lincoln and his crew of unruly pirates.
Though Nola convinces the buccaneers of the Sybil Curse, to take her to safe passage, the seven-day journey takes them on an adventure they never imagined. Amidst massive waves, sea monsters, and dragons, arises a bond that cannot be broken⁠—the love between sworn enemies.