Scorpion in the Sea by P. T. Deutermann
This novel begins with strange sightings occurring off the coast of northern Florida. A fishing boat disappears on a calm night with no survivors. Patrols from the Mayport Naval Station detect something strange out there, but can't pinpoint its identity. . . or a motive for the threat. Commander Mike Montgomery, skipper of the obsolete destroyer "Goldsborough", is skeptical at first. As the evidence mounts, however, he becomes a believer. At sea the incidents and the suspense mount until the terrible mission of the unseen intruder erupts in tragedy and final, horrific confrontation with the " Goldsborough".
Author Biography: P.T. Deutermann is a retired navy captain and a distinguished graduate of the Naval War College. He was chief of arms control negotiations for the Joint Chiefs of Staff and commanded a destroyer squadron in the Pacific Fleet.