Pitt angled his head downward so the lights on his hardhat pointed directly to the front. It was a wasted motion. The passage was soon filled with a mist that rose out of the water like steam. Pitt had a sudden vision of going over Niagara Falls without a barrel. The roar was deafening now, magnified by the acoustics of the rocky cavern. And then Giordino passed into the mist and vanished.

    Pitt could only hold on to the canister and watch with strangely paralyzed fascination as he was enveloped by the spray. He braced himself for an endless fall. But the endless fall never came. The thunder came not from the river plunging downward, but from a furious torrent that crashed down from above.

    He was pummeled by a surging deluge that burst in a great plume from the limestone roof of the cavern. The huge torrent of water barreled down a tributary that fed into the subterranean river from another source. Pitt was baffled by the sight of so much water rushing under an and and thirsty desert no farther away than the distance a good outfielder could throw a baseball. He decided that it must feed into the river by great pressure from a system of underground aquifers.

    Once through the curtain of mist, he could see the walls had spread and the roof sloped upward into a chamber of vast size and proportion. It was a bizarrely decorated cavern filled with grotesquely shaped helictites, a family of stalactites that ignores gravity and grows in eccentric directions. Mineral deposits had also formed beautifully sculpted mushrooms over a meter tall and delicate gypsum flowers with graceful plumes. The spectacular formations would have been described by veteran spelunkers as a showcase grotto.

    Pitt couldn't but wonder how many other subterranean worlds sprawled through the earth in eternal darkness, waiting to be discovered and explored. It was easy to let the mind run amok and imagine a long-dead and lost race who had lived down here and carved the magnificent calcite sculptures.

    Not Giordino. The beauty was lost on him. He turned, gazed back at Pitt with a big I'm-glad-to-be-alive smile and said, "Looks like a hangout for the Phantom of the Opera."

    "I doubt if we'll find Lon Chaney playing the pipe organ down here."

    "We have a landing thirty meters ahead to the left," Giordino said, his spirits lifting considerably.

    "Right. Start your turn into shallow water and swim like hell to get out of the main current."

    Giordino needed no urging. He cut his angle sharply, pulling the canister behind him and kicking his fins furiously. Pitt released his grip on the big aluminum tube, swam strongly alongside until he was at its midpoint, and then, using his body as a drag, he heaved it after Giordino.

    The approach worked as Pitt had hoped. Giordino broke free of the current and swam into calmer water. When his fins touched the bottom, he climbed ashore, dragging the canister with him.

    Now unhampered, Pitt easily stroked into the shallows, landing ten meters below Giordino. He crawled out of the water, sat down, removed his fins and goggles, and carefully walked back upstream across the smoothly textured rocks as he removed his air tanks.

    Giordino did the same before he began dismantling the canister. He looked up at Pitt with a look of profound accomplishment. "Nice place you've got here."

    "Sorry for the mess," muttered Pitt, "but the seven dwarfs are on a break."

    "Does it feel as good to you as it does to me that we've come this far?"

    "I'm not sad to be alive, if that's what you mean."

    "How far have we come?"

    Pitt tapped in a command on the computer strapped to his arm. "According to my faithful wonder of technology, we have traveled two kilometers through damnation and dropped another two meters toward hell."

    "Twenty-eight to go."

    "Yes," Pitt said, smiling like a magician about to bedazzle an audience. "But from here on, we go in style."

    Five minutes later the eight air chambers of the Wallowing Windbag were filled and the hull fully inflated, deployed, and ready to do battle with the river. Known as a water rescue response vehicle, the ungainly Hovercraft could ride on a cushion of air effortlessly over boiling rapids, quicksand, thin ice, and polluted quagmires. Vehicles in use by police and fire departments around the country had saved countless victims from death by drowning. Now this one was going on an endurance trial its builders never conceived.

    Three meters (10 feet) in length and 1.5 meters (5 feet) wide, the compact craft mounted a four-cycle, 50-horsepower engine that could propel her over a flat surface at 64 kilometers (40 miles) an hour.

    "Our engineers did a fine job of modifying the height," said Giordino.

    "Adopting a horizontal engine and fan was a stroke of genius," Pitt agreed.

    Amazing how much equipment they crammed inside the canister."

    Before they cast off, they stowed and tied down ten reserve air tanks, extra air bottles to reinflate the Hovercraft, a battery of lights including two aircraft landing lights built into waterproof housings, spare batteries, first aid equipment, and three additional breathing regulators.

    From a watertight container Pitt retrieved his battered, old .45 Colt automatic and two ammo clips. He smiled as he also found a thermos of coffee and four bologna sandwiches. Admiral Sandecker never forgot the details that make for a successful operation. Pitt put the thermos and sandwiches back in the container. There was no time for a picnic. They had to push on if they were to reach the treasure chamber before it was too late to save Loren and Rudi. He inserted the gun and extra ammo clips into a plastic bag and sealed the opening. Then he unzipped the front of his wet suit and slipped the bag inside next to his stomach.

    He stared for a moment at the black collapsible Hovercraft. "Oh, Circe, who will guide us on this journey," he quoted. "To Hades no man ever went in a black ship."

    Giordino looked up from coupling a pair of steering oars to their locks. "Where did you hear that?"

    "The Odyssey by Homer."

    "Verily among the Trojans too there be men that dive," Giordino recited glibly. "The Iliad. I can quote Homer too."

    "You never cease to amaze me."

    "It's nothing really."

    Pitt climbed aboard. "Gear stashed?"

    "All buttoned down."

    "Ready to shove off?"

    "Start her up."

    Pitt crouched in the stern just ahead of the engine fan. He engaged the starter and the air-cooled engine sputtered to life. The small engine was well muffled and the exhaust sounded only as a muted throb.

    Giordino took his position in the bow of the craft and turned on one of the landing lights, illuminating the cavern as bright as daylight. He looked back at Pitt and laughed. "I hope no one fines us for polluting a virgin environment."

    Pitt laughed too. "A losing proposition for the local sheriff. I forgot my wallet."

    The Hovercraft moved off the shoreline, suspended on its self-produced 20-centimeter (8-inch) cushion of air into the mainstream of the river. Pitt held the vertical grips of the control bar in each hand and easily steered an arrow-straight course over the flowing current.

    It seemed strange to be skimming over the water surface without a sensation of contact. From the bow, Giordino could look down into the remarkably transparent water that had turned from the cobalt blue of the sinkhole to a deep aqua green and see startled albino salamanders and small schools of blind cave fish darting amid the spherical boulders that carpeted the river bottom like fallen ornaments. He kept busy reporting the river conditions ahead and snapping photos as Pitt maneuvered and recorded data on his computer for Peter Duncan.