Frederik Pohl & Jack Williamson 
Undersea Quest 

A missing relative…Something of value was buried beneath the underwater dome city of Marinia…something that had already cost one man’s life, caused another man’s kidnapping and gravely affected still another man’s future.Expelled from the Sub-Sea Academy on trumped-up charges, Jim Eden wasn’t about to wait around to prove his innocence. As soon as he leaned that his uncle mysteriously disappeared while mining uranium at the bottom of hazardous Eden Deep, Jim knew what he had to do…and that he had to do it fast.So he headed for the vast dome city — location of the great mining colony at the bottom of the sea — to pick up any clues to his uncle’s disappearance. But once he had entered the undersea metropolis, the wrong people had his number…and they were determined that Jim would sink forever without a trace.