Riptide by Douglas Preston, Lincoln Child

paused,
     a trace of a smile on his lips—“between 1.8 and 2 billion dollars.”
    There was a long silence, filled by the throbbing of the engine, the monotonous wheeling of the gulls, and the sound of the
     boat moving through the water. Hatch struggled to grasp the enormity of the sum.
    Neidelman lowered his voice. “That is, not including the value of St. Michael’s Sword, Ockham’s greatest prize.”
    For a moment, the spell was broken. “Come on, Captain,” Hatch said with a laugh. “Don’t tell me you believe such a mossy old
     legend.”
    “Not until I read Macallan’s journal. Dr. Hatch, it
is
there. Macallan watched them bury it with the treasure.”
    Hatch stared unseeing at the deck, his mind a turmoil.
This is incredible, almost beyond belief…
    He glanced up and felt the muscles of his gut tighten involuntarily. The countless questions that had risen within him suddenly
     evaporated. Across the expanse of sea, he could now make out the long, low fog that concealed Ragged Island, the same fog
     bank that had lain on the island more than twenty-five years before.
    He heard Neidelman next to him, saying something. He turned, breathing shallowly, trying to quiet his beating heart. “I’m
     sorry?”
    “I said, I know you have little interest in the money. But I wanted you to know that in the agreement I’ve proposed here,
     you would receive half the treasure, before expenses. In return for my undertaking all the financial risk, I will receive
     St. Michael’s Sword. Your share would therefore be in the vicinity of one billion dollars.”
    Hatch swallowed. “You’re right. I couldn’t care less.”
    There was a long pause, then Neidelman raised his binoculars and examined the island of fog. “Why does it remain fogbound?”
    “There’s a good reason,” Hatch said, grateful for the change of topic. “The island’s powerful riptide deflects the frigid
     Labrador Current into the warm Cape Cod Current, and where they mix you get a large eddy of fog. Sometimes only a thin ring
     of fog surrounds the island, other times it’s totally socked in.”
    “What more could a pirate ask for?” Neidelman murmured.
    It won’t be long now,
Hatch thought. He tried to lose himself in the hissing of water racing along the chine, the briny scent of the air, the cool
     brass of the wheel against his palms. He glanced at Neidelman, and saw a muscle twitching in his set jaw. He was also experiencing
     a powerful emotion, of another though no less private kind.
    The patch of fog drew closer. Hatch struggled in silence, willing himself to keep the boat pointed in the direction of the
     creeping fingers of mist, so strangely alien on a horizon that had otherwise grown clear. He eased down the throttle as the
     boat nosed its prow into the murk. Suddenly, clamminess surrounded them. Malin could feel droplets of condensation begin to
     form on his knuckles and along the back of his neck.
    He strained to see through the fog. A dark, distant outline seemed to appear, only to vanish again. He cut the throttle further.
     In the relative quiet, he could now hear the sound of surf, and the ringing of the Ragged Island bell buoy, warning mariners
     away from its treacherous reefs. He swung the boat in a more northerly course, to bring it around the leeward end of the island.
     Suddenly, a ruined iron derrick loomed above the mists about two hundred yards off the port side, twisted by storms, streaked
     with rust.
    With a short intake of breath, Neidelman swiftly raised the binoculars to his eyes, but the boat had plunged into another
     patch of fog and the island disappeared once again. A chill wind had picked up and a light drizzle began to fall.
    “Can we get closer?” Neidelman murmured.
    Hatch steered the boat toward the reefs. As they entered the lee of the island, the surf dropped along with the wind. Abruptly,
     they broke through the circle of mist and the island stood revealed in its entirety.
    Hatch brought