This is the debut novel written by author Jade Shyback. I believe this is the first book in the new young adult series. While the focus may be young adult, I am a senior fan and will definitely be watching for the next book in this series.
Earth is in trouble. It has become impossible for life to live on the surface of the planet. Marisol Blaise and her family were struggling to survive. One after the other of her family was succumbing to extreme conditions. Her mother begged a couple to take her with them to Aqueous, the underwater community. The couple had no children and treated her as their own.