Escape undersea
(Book)

"Invited to the world's only undersea research station, the Skylar family heads to the Florida Keys and dives into an unexpected adventure. While visiting their ex-military friends in the Aquarius Sea Station, Ezzy and Luke encounter a strange algae bloom at the surface, giant goliath groupers, and a mysterious fish that threatens the coral reefs and their own safety. Once again, they unwittingly stumble into a plot that could have disastrous consequences for the local wildlife and must jump into action to save the day."