After a stint in the U.S. Air Force, he became a copywriter and, later, creative director of two of the country's leading ad agencies. In 1965 he started writing novels; he penned 13 that star a character whose name is synonymous with action adventure her s. This author now has 70 million books in print in 40 languages, sold in some 105 countries. Last year his first nonfiction book was published by Simon &Schuster. Guessed it yet? The gentleman is Clive Cussler, whose The Sea Hunters: True Adventures with Famous Shipwrecks has berthed this week on our mass market list -- a chart generally populated only with fiction. The Pocket edition was launched on July 15 with a one-million-copy first printing. Like his hero Dirk Pitt, Cussler has had a lifelong love affair with the sea and its great ships. After organizing an unsuccessful search for John Paul Jones's Revolutionary War ship, the Bonhomme Richard, Cussler became hooked on hunting for shipwrecks. With his book royalties, he created the National Underwater &Marine Agency (NUMA), a nonprofit organization that discovers and preserves historic shipwrecks. In The Sea Hunters, Cussler describes -- with co-author Craig Dirgo -- 12 of the more than 30 expeditions he has conducted to find these wrecks (whose artifacts he donates to museums across the country).