huck, seventeen, and his diving partner, Tom Prior, about thirty, have earned money by retrieving old sunken anchors and selling them. However, when red Bowers, an odd man, sells them his yacht which has just sunk in a storm, they irect all energies to ""raising the Dubhe."" Progress is rapid, until Chuck tangles with a deadly white shark and is afraid to dive again. David Bowers, Fred's son, agerly joins the two divers; Chuck subsequently decides he must go down again, and on the second dive encounters the shark, and rescues David. The descriptions of marine life are sharp; the discussions of the intricacies of diving seem authentic -- almost instructive. Chuck is the only character whom the author develops to any extent, but it's a sure fire subject.