Crisis on Conshelf Ten
While visiting Conshelf Ten, an underwater colony on Earth, a young Moon boy becomes involved with dissident Gillmen whose plans threaten the whole world.
Science fiction, Sea stories, Fiction, general, Children's fiction, Fantasy fiction
Monica Hughes        
Monica Hughes OC (November 3, 1925 – March 7, 2003) was an English-Canadian author of books for children and young adults, especially science fiction. She also wrote adventure and historical novels set in Canada, and the text for some children's picture books. She may be known best for the Isis trilogy of young-adult science fiction novels (1980–1982).

**Source**: [Monica Hughes](https://en.wikipedia.org/wiki/Monica_Hughes) on Wikipedia.