Seabound by Jordan Rivet

Esther has lived on a cruise ship for sixteen years, ever since she fled an apocalyptic catastrophe with a handful of desperate survivors. When disaster strikes the water system on Esther’s watch, she’s thrust into an adventure that will threaten the lives of everyone she loves.

In danger of running out of drinking water, Esther and her friends sail for a mysterious floating metropolis called the Galaxy Flotilla. The flotilla’s residents—including their handsome and enigmatic spokesman—parade their lives of luxury before the newcomers, but they’ll want something in return for their warm welcome.

Esther doesn’t trust the elegant Galaxy inhabitants, and she may be the only one who sees the threats lurking beneath the surface. When a sudden storm reveals a new peril, Esther will risk everything to save her friends—and her ship—before the sea claims them at last.