Undersea Trilogy Series by Frederik Pohl, Jack Williamson

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 learned that his uncle mysteriously disappeared while mining uranium at the bottom of hazardous Eden Deep, Jim knew what he had to do.. moreA 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 learned 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. less

MONSTERS OF THE DEEP....Everyone at the academy knew that sea serpents were, without doubt, silly superstitions. Everyone but David Craken, that is. This young cadet from Marinia had been born and raised four miles beneath the waves, and he knew that more than rich new fuel sources and precious stones lay in wait for the men who dared invade this last frontier... moreMONSTERS OF THE DEEP....Everyone at the academy knew that sea serpents were, without doubt, silly superstitions. Everyone but David Craken, that is. This young cadet from Marinia had been born and raised four miles beneath the waves, and he knew that more than rich new fuel sources and precious stones lay in wait for the men who dared invade this last frontier. But when David dived into the depths at thirteen hundred feet and disappeared -- only to reappear, drifting offshore months later -- his friend Jim Eden learned there was more truth to certain superstitions than he cared to believe. On a strange and hazardous journey, Jim and the men of the sub-Sea Academy suddenly found themselves up against the dangerous creatures of the deep -- and embroiled in a life-against-life adventure they would never forget! less

SEAQUAKEIt was the most dreaded of all undersea phenomena. If strong enough, it would set up chain-reaction pressures that could shatter any dome and cost inestimable lives. But the Krakatoan Dome has been specifically designed to cope with the tremors of its seaquake-prone area. The trouble was, all of a sudden, there were more quakes than any of the experts had counted on...quakes that no one could possibly have forecast because they hadn't come from natural causes... moreSEAQUAKEIt was the most dreaded of all undersea phenomena. If strong enough, it would set up chain-reaction pressures that could shatter any dome and cost inestimable lives. But the Krakatoan Dome has been specifically designed to cope with the tremors of its seaquake-prone area. The trouble was, all of a sudden, there were more quakes than any of the experts had counted on...quakes that no one could possibly have forecast because they hadn't come from natural causes.The Sub-Sea Academy had assigned Cadet Jim Eden to the Krakatoan Dome to find out what was going on, and for very special reasons. First, he was more at home in the underwater world than most anyone else. But, even more important, they sent Jim because his uncle was suspected of being the heinous saboteur! less

The story takes place in and around the underwater dome city called Marinia. The hero of the stories is cadet Jim Eden of the Sub-Sea Academy.