English pirate, "Red Ned" Ockham was born in 1662 in Cornwall and educated at Harrow and Oxford. He began his seafaring career in the British Navy in which he distinguished himself against the Spanish. Tiring of the regimentation he was granted a letter of marque by the Admiralty. Operating as a privateer, he captured a number of choice prizes which he was required to share with his government. So much for that! In 1685 he took up slaving but after being trapped in a blockaded harbor by two ships of the line he set his ship afire as a diversion and escaped—alone. Over the next ten years Ockham became the most notorious pirate in the Atlantic, inventing many of the most ruthless and cunning pirate techniques, like walking the plank, for instance. The final triumph of his career was the capture and plunder the Spanish flota de plata, acquiring in that single feat a treasure estimated at over a billion dollars in face value alone.

Neat stuff in retrospect—but why do you want to know all this about a 15th century pirate? Because old "Red Ned" is the inspiration for a dandy new cliffhanger called Riptide by Douglas Preston and Lincoln Childs (Warner Books; 417pp; $25.00). The pirate disappeared mysteriously in 1697. His command ship was found drifting free off the Azores, all hands dead and not a trace of treasure. A prologue brings the reader to the present by chronicling the misbegotten fate of 25 treasure hunters since 1790 when a Maine cod fisherman, was blown onto (a fictitious) Ragged Island. He found a block and tackle hanging from an ancient oak above suspicious depression in the ground and declared the island the site of pirate treasure.

Our '90s hero, Dr. Malin Hatch, is a survivor. In his youth he survived the forbidden trip to Ragged Island one summer day when he and his brother became too bored not to find trouble. He is also the surviving member of a family destroyed by an obsession with the treasure. His grandfather, a wealthy New York financier brought his family to Maine for the summer, learned of the legend, bought the island and within two years lost the family fortune, declared bankruptcy, drank himself to death. Presumably, Dr. Hatch put himself through med school delivering pizzas—all he has inherited of the family fortune is Ragged Island.

Enter Captain Gerard Neidelman, treasure hunter. One of the masterful aspects of this thriller is the way the Captain is presented. Most of the characters are on the bland side (which is not important because the situation is so taut) but Neidelman is inscrutable from beginning to almost the end. Neidelman propositions Hatch and the two of them meet on Ragged Island to commence the dig.

Another masterful aspect of Riptide is the array of up-to-the-minute treasure hunting paraphernalia Neidelman's company, Thalassa, hauls to the site—"more computing power than a small university" and the nerds to run it, titanium beams, atomic pumps three company boats, one outfitted as a lab and so on. Thalassa personnel is also pretty exotic—a French caribe archeologist named Bonterre (watch the names), a company historian who has discover that the treasure pit was designed by a kidnapped English architect whose specialty was cathedrals, and a paranoid Vietnam vet whose life was saved by Neidelman in the deep past.

The treasure is buried in a labyrinth of watery tunnels which fill and empty with the tide. Tension builds with every foot of tunnel gained. Casualties build, mysteries, both medical and historical multiply. In the tradition of Ahab and Nemo, Captain Neidelman digs on…