Sad Wind From the Sea - Jack Higgins

A gunrunner's hunt for a fortune in gold leads to a life-and-death struggle in Communist China
Mark Hagen's streak of bad luck left him broke, despondent, and barely able to eke out a living smuggling guns in Macao. But things begin to look up when Hagen gets a lead on a bounty of gold, lying untouched at the bottom of a lagoon in the marshes of southern China. Unfortunately for Hagen, he's not the only one after the sunken treasure, and the race to the gold quickly escalates into a bloody struggle for survival on the treacherous waters of the South China Sea.