Aquarium diver hopes novel makes a splash

Myrtle isn't big on plotlines, but the 600-pound giant sea turtle appreciates a writerly touch whenever she can get it.

"She loves to get her shell scratched," says John H . Hanzl, diving safety officer at the New England Aquarium. Hanzl's first novel, "Out of Hell's Kitchen," was published in September.

"I'll go down near the bottom, and she'll wait for me to grab a conch shell and scratch her back," he says of one of his favorite underwater characters.

Hanzl is responsible for overseeing more than 4,000 underwater operations for the aquarium each year, meaning anything from feeding stingrays and sand tiger sharks at its downtown location to traveling as far as the Caribbean and the South Pacific to collect specimens for exhibits or to protect through conservation.

But as he was training to become a diving instructor almost 10 years ago, traveling on an expedition near the coast of Cuba, the 42-year-old South End resident had a literary revelation that prompted him to get his feet wet in a different trade.

"I was reading some action adventure stories at the time, and I became frustrated with the fairly low believability factor and even the quality of some of the writing," he says.

"I figured that I could at least do as well as the guys I was reading, but, if not, I wanted to prove myself wrong."

After years of toiling away at the keyboard in his off hours, Hanzl is putting that theory to the test with his first novel, a suspense story he describes as "a rip-roaring good yarn with, of course, some great high seas and diving adventures."

It tells the tale of Luke Hawthorn, an 18-year-old who, after his London home is destroyed in a blaze that takes the life of his mother, is taken in by an uncle he meets for the first time at his mother's funeral. Complex human entanglements, no giant sea turtles in sight.

Before Hanzl could put pen to paper, he got the ball rolling by drafting a 34-page outline, laying the foundation for its sequence of parallel plots.

"I couldn't write the first chapter until I had a really strong idea of what the story was all about," says Hanzl, who has lived in Boston since graduating from Boston University in 1987.

"I had to make sure everything I was writing was based on fact and anything in the story could happen in real life."

Part of that process involved incorporating personal experiences such as sky diving, rock climbing, and a motorcycle accident Hanzl was involved in years ago.

An advantage of that style of research is that it generates an incentive to get working on a follow-up story, he says, adding that a sequel would provide "a reason to continue experiencing these things and traveling to different places."

On a recent weekday afternoon, Hanzl stood over the four-story, 200,000-gallon tank at the aquarium, as four young children watched his every move. Leaning against a wooden rail at the top of the observation deck, he tossed a compact block of corn and peas into the tank for his aquatic companions below.

To one of the pint-size spectators who wondered aloud what made the splash, the diving officer, ever the adventure writer, replied casually that it was "just a block of human flesh," choosing to let his words register for just a moment in muffled gasps from his young audience. And then he quickly set the record straight.

Richard Thompson can be reached at rthompson@globe.com.