The Sea Symphony: The Sea Symphony Trilogy Book 1

The Sea Symphony is set in a world completely far away from our own: a land where everything is sea except for a small fishing island called Whale Cove, where Astaroth and Calliope reside.

Every year, in the village cove, a Crystal Palace emerges from the waters and chooses an islander to "take him to the afterlife". This is an act of celebration in honor of the event, but something goes wrong the same night the Palace emerges, it breaks into pieces and, in the water, a black, viscous substance covers everything. Encouraged to save his people, Astaroth sets course for the open sea together with Calliope to follow the trail of this strange enemy, along with a little black cat named Vela...