Abyssal - Ripley Shaine

Exo-marine biologist Arizona Birch chooses Thalassa-IX because it is distant, silent, and forgotten-an icy ocean world far from the gravity of her father's death.

The posting promises solitude and closure. Instead, it offers a reckoning. The research station she touches down on is barely functional, staffed by a skeletal crew and surrounded by a collapsing marine ecosystem. Worse still, the walls themselves are alive-lined with a vast neural linked coral structure no one can fully explain. As Arizona digs through her father's legacy, she realizes Thalassa-IX was not an escape from his legacy but its endpoint. 

Her father did not simply study the deep. He reshaped it.

At the heart of the dying ocean lurks a genetically engineered leviathan, grown using his own DNA-an organism that has devastated the planet's biodiversity and refuses to stay buried. As Arizona begins to experience its memories, instincts, and hunger as her own, the boundary between scientist and creation erodes. With the fate of Thalassa-IX (and herself) hanging in the balance, Arizona must confront the cost of scientific ambition and decide whether to destroy the last living fragment of her father... or allow it to complete the work he began.

Perfect for fans of authors like S.A. Barnes or Darcy Coates.