Death Wore Fins, by Ronal Kayser (writing as Dale Clark) (epub/Kindle/pdf)

Though he did work for a small-town newspaper, Ken Svederup had been around, and to him the expense-paid trip he had won for a front-page news beat seemed pretty phony. But never look a gift horse... He was off to meet the Big Boss in California -- and no doubt he’d get the real story.

Ken did meet the Big Boss, but he had not anticipated Clara Kelly, whose beauty and peppery temper made him forget the girls back home in Milquevais, Minnesota.

And the story was revealed...through a body pulled from the pounding surf after what seemed a deep-sea accident...and Ken found himself on the trail of an underwater killer.