At 83, novelist Clive Cussler still scuba dives, in the spirit of his younger and best-known fictional character, marine adventurer Dirk Pitt. So asking Cussler about retiring from writing makes him laugh.

“Hell, no,” he snaps. “I’m not quitting.” He jokes that someday in his writing shed behind his home in Paradise Valley, Ariz., “they may find me behind the computer, just bones and cobwebs.”

This year, Cussler has four new novels, each one the latest in a series written with a collaborator. First is The Assassin (March 3, Putnam), the eighth entry cowritten with Justin Scott and starring Isaac Bell, an early 20th-century private detective with a sense of justice and humor. Cussler has previously published 58 novels, four nonfiction books and two children’s books and consistently hits the bestseller lists.

By himself, he wrote 17 Dirk Pitt novels, starting with The Mediterranean Caper in 1973. About 15 years ago, Cussler says, his then-publisher, Simon and Schuster, suggested working with coauthors to publish more frequently. If some dismiss that as an assembly-line approach to commercial fiction, Cussler “doesn’t give a damn. I never had a highfalutin view of what I write. It’s a job. I entertain my readers. I get up in the morning and I start typing.”

In his five series Cussler now works with five coauthors, including his 53-year-old son, Dirk, who after a career in finance, cowrote the last six Dirk Pitt novels. Cussler named Pitt after his son who, as a three-year-old, “used to fall asleep listening to me tapping on an old portable Smith Corona typewriter.”

Cussler says he works with his cowriters on developing the plots. “The biggest challenge usually is not the beginning or the end,” he says, “but the middle, keeping the action moving.” His coauthors write the first 50 or 100 pages “and send it to me, and I make changes and send it back. And so it goes.” Cussler still works eight hours a day, six days a week, but does more rewriting than writing.

If there’s a problem, he adds, it’s that cowriters “tend to overwrite. I want it to be easy to read. I’m not writing exotic literature. I like snappy dialogue and short descriptions and lots of action.”

In The Assassin, Isaac Bell, one of Cussler’s recurring heroes, is described as “a tall man in a white suit, with a handsome head of golden hair, an abundant mustache, and fierce blue eyes.” He’s “well over six feet, but lean as wire rope on a one-hundred-seventy-five pound frame. A head held high and a self-contained gaze signified life at full tide.”

Bell works for the Van Dorn Detective Agency, which Cussler based on the real-life Pinkerton Agency. The last book in the series, The Bootlegger, set during Prohibition, landed at No. 2 last March on Publishers Weekly’s hardcover fiction best-seller list. A PW review of The Bootlegger noted, “Early books in the series were near parodies of period potboilers, but more recent entries will impress thriller readers as laudable historical action novels.”

In The Assassin, Bell is hired by a government agency to investigate John D. Rockefeller’s Standard Oil monopoly. Set in Pennsylvania, Kansas, Texas, Washington, D.C., New York, and Russia’s war-torn Baku oil fields on the Caspian Sea, the story takes a deadly twist when a skilled sniper starts killing opponents of Standard Oil. For most of the novel, it’s not clear if Rockefeller is behind the murders.

Cussler says research remains “my labor of love. I like to take something that happened, a bit of history and twist it and play with it.” Reading about the real-life Rockefeller, he says, was “fascinating. He was seen by many as a nasty, old mogul who’d do anything to his competitors, but he also had some good points. At the end of his life, he gave away money like he was doing penance.”

In The Assassin, Cussler lets Rockefeller defend his business practices: “The outcry against us is wrong. The public cannot seem to understand that we are not monsters. We are merely efficient, enormously more efficient than our competitors. Oil is not the biggest business in America. Coal is bigger. Railroads are bigger. Steel is bigger. Yet, we own coal. We control railroads. We own steel. Why? Not because we’re monsters, but because they are chaotic, embroiled in murderous rivalry, each conducting his own business independently of the other and in sharp competition. We cooperate.”

Cussler’s own life and career is a blend of imagination and reality, art that imitates life and life inspired by art. As an Air Force mechanic in Hawaii during the Korean War, he discovered a passion for scuba diving when it was so new, “we had to send to France, to (Jacques) Cousteau for the tanks.”

After the war, Cussler worked in advertising for 15 years and began writing fiction only after his first wife, Barbara (who died in 2003), started working nights. “After I put the kids to bed,” he says, “I had nothing to do and no one to talk to, so I thought I’d write an adventure story. But it’s not like I had the great American novel burning in me.”

He grew up in Alhambra, Calif., and dropped out of Pasadena City College after two years to join the Air Force during the Korean War. But he was an avid reader, and a fan of Edgar Allan Poe, Travis McGee, and his favorite novelist, Alistair MacLean.

Cussler decided to play with what he knew or could imagine about underwater exploration. Pitt was cast as the troubleshooter and ultimately the director of an organization Cussler imagined: the National Underwater Marine Agency, which discovered and conserved shipwreck artifacts.

It took him three years to find a publisher. He didn’t hit the bestseller until his third Pitt adventure, Raise the Titanic!, was released in 1976. It imagines Pitt and his crew actually raising the remains of the Titanic, which may contain a rare mineral sought by the CIA and Soviet spies.

Three years later, Cussler turned a fictional device into fact. He organized a nonprofit agency aimed at finding and preserving maritime history. As in his novels, he called it the National Underwater Marine Agency. It has found more than 60 underwater wrecks, including the remains of the Carpathia, which had rescued Titanic survivors and the Confederate submarine, the H.L. Hunley, sunk in Charleston Harbor. “We are not treasure hunters,” he says. “We go after shipwrecks and artifacts and donate them to museums or government agencies.”

In 1997, Cussler’s first nonfiction book about underwater exploration, The Sea Hunters, triggered what he thought was going to be an honorary doctorate from the State University of New York Maritime College in the Bronx. But in an unprecedented surprise, the college awarded Cussler an actual doctorate, accepting his book as the equivalent of a Ph.D. thesis.

But he doesn’t like to be called “Dr. Cussler,” and says, “I’ve never used that title.” Although he’s often described as a marine archeologist, he calls himself “a dilettante who loves the challenge of solving mysteries, and there’s no greater mystery than a lost shipwreck.”

He enjoys two other passions: collecting antique guns and antique cars, which often are mentioned in his novels. (In The Assassin, Bell drives a red Locomobile, an early luxury vehicle.) Cussler’s daughter, Teri, turned his collection of 100 classic cars, including a 1911 Locomobile, into the Cussler Museum in Arvada, Colo.

His success in publishing, however, has not extended to Hollywood. Two of his novels were turned into what he labels “lousy” films. Raise the Titanic!, starring Richard Jordan as Pitt, lost so much money that producer Lew Grade told the Los Angeles Times that, “It would have been cheaper to lower the Atlantic.”

The 2005 film version of Sahara starring Matthew McConaughey as Pitt, out to save the Earth, was also a box office bomb. It lead to a long legal battle between Cussler and the movie studio, Crusader Entertainment, that ended in a draw. A jury found that both sides had breached their contracts. Cussler says only that’s he finished with Hollywood, which he finds “really weird.”

His collaboration with his son began in 2004, after Dirk Cussler, working as a controller at Motorola Iridium in Phoenix, faced a possible transfer to Chicago. He decided it was time for a career change and “was fooling around with writing a nonfiction story on aviation,” when Cussler asked him if he wanted to help write a Pitt novel.

“After peeling myself off the floor,” Dirk Cussler says, “I said yes, and we’ve been charging along ever since.” Their seventh collaboration, as yet untitled, is expected to be published in 2016.

Which raises a question for Clive Cussler: Given all his coauthors, will his series continue after he’s gone?

He says only, “I hope Dirk Pitt will go on after me.”

His son adds, “Pitt is such an iconic American hero that it would be difficult to see him fade away. I would certainly respect my father’s wishes as to his literary creation and would be more than happy to see Pitt swashbuckling his way across the seas for years to come.”

Bob Minzesheimer, a former reporter and book reviewer for USA Today, is a freelance writer based in Ossining, N.Y.