The Neptune Challenge

In a future where Earth's oceans are dying, a young girl named Nere is one of the last remaining 'Neptunes,' humans genetically engineered to live underwater. When a mysterious illness threatens her undersea colony, Nere must embark on a dangerous mission to the surface world, a place she's only heard about in stories. She faces perilous challenges and uncovers secrets that could save her people or doom them forever.