Driving by the sonar and radar probes of the computer instead of relying on his limited vision under the DSMV’s lights did not make for a joy ride. The strain was beginning to arrive in aching muscles and sore eyes, and he decided to turn temporary control over to Plunkett, who had quickly picked up the intricacies of operating Big John.

“We’ve just passed the two-thousand-meter mark,” Pitt reported.

“Looking good,” replied Plunkett cheerfully. “We’re better than halfway.”

“Don’t write the check just yet. The grade has steepened. If it increases another five degrees, our tracks won’t be able to keep their grip.”

Plunkett forced out all thoughts of failure. He had complete confidence in Pitt, a particular that irritated the man from NUMA to no end. “The slope’s surface has smoothed out. We should have a direct path to the summit.”

“The lava rocks hereabouts may have lost their sharp edges and become rounded,” Pitt muttered wearily, his words coming slow with the edge of an exhausted man, “but under no circumstance can they be called smooth.”

“Not to worry. We’re out of the abyssal zone and into midwater.” Plunkett paused and pointed through the viewing window at a flash of blue-green bioluminescence. “Porichthys myriaster, a fish that lights up for two minutes.”

“You have to feel sorry for him,” Pitt said tongue-in-cheek.

“Why?” Plunkett challenged. “The porichthys has adapted very well. His luminescence is used to frighten predators, act as bait to attract food, as a means to identify his own species and, of course, attract the opposite sex in the total blackness.”

“Swimming in a cold black void all their lives. I’d call that a real drag.”

Plunkett realized he was being had. “Very clever observation, Mr. Pitt. A pity we can’t offer midwater fish some sort of entertainment.”

“I think we can give them a few laughs.”

“Oh, really. What have you got in mind?”

“They can watch you drive for a while.” He gestured to the control console. “She’s all yours. Mind you keep a tight eye on the monitor’s geological display and not on jellyfish with neon advertising.”

Pitt slouched in his seat, blinked his eyes closed, and looked to be asleep in a moment.

Pitt came awake two hours later at the sound of a loud crack that came like a gunshot. He immediately sensed trouble. He came erect and scanned the console, spying a flashing red light.

“A malfunction?”

“We’ve sprung a leak,” Plunkett informed him promptly. “The warning light came on in unison with the bang.”

“What does the computer say about damage and location?”

“Sorry, you didn’t teach me the code to activate the program.”

Pitt quickly punched the proper code on the keyboard. The readout instantly swept across the display monitor.

“We’re lucky,” said Pitt. “The life-support and electronic equipment chambers are tight. So is the shielded reactor compartment. The leak is below, somewhere around the engine and generator compartment.”

“You call that lucky?”

“There’s room to move around in that section, and the walls are accessible for plugging the entry hole. The battering this poor old bus has taken must have opened a microscopic casting flaw in the lower hull casing.”

“The force of the outer water pressure through a hole the size of a pin can fill the interior volume of this cabin in two hours,” Plunkett said uneasily. He stirred uncomfortably. The optimism had gone out of his eyes as he stared bleakly at the monitor. “And if the hole widens and the hull collapses…” His voice dropped off.

“These walls won’t collapse,” Pitt said emphatically. “They were built to resist six times the pressure of this depth.”

“That still leaves a tiny shaft of water coming in with the power of a laser beam. Its force can slice an electric cable or a man’s arm in the wink of an eye.”

“Then I’ll have to be careful, won’t I?” Pitt said as he slipped out of his chair and crawled toward the aft end of the control cabin. He had to maintain a constant handhold to keep from being thrown about by the swaying and pitching of the vehicle as it lurched over the broken terrain. Just before reaching the exit door, he leaned down and lifted a small trapdoor and switched on the lights, illuminating the small confines of the engine compartment.

He could hear a sharp hiss above the hum of the steam turbine but couldn’t see where it was coming from. Already there was a quarter meter of water covering the steel walk matting. He paused and listened, trying to locate the sound. It wouldn’t do to rush blindly into the razor-slashing stream.

“See it?” Plunkett shouted at him.

“No!” Pitt snapped nervously.

“Should I stop?”

“Not for anything. Keep moving toward the summit.”

He leaned through the floor opening. There was a threatening terror, a foreboding about the deadly hissing noise, more menacing than the hostile world outside. Had the spurting leak already damaged vital equipment? Was it too strong to be stopped? There was no time to lose, no time to contemplate, no time to weigh the odds. And he who hesitated was supposed to be lost. It made no difference now if he died by drowning, cut to ribbons, or crushed by the relentless pressure of the deep sea.

He dropped through the trapdoor and crouched inside for a few moments, happy to still be in one piece. The hissing was close, almost within an arm’s length, and he could feel the sting from the spray as its stream struck something ahead. But the resulting mist that filled the compartment prevented him from spotting the entry hole.

Pitt edged closer through the mist. A thought struck him, and he pulled off a shoe. He held it up and swung it from side to side with the heel out as a blind man would sweep a cane. Abruptly the shoe was nearly torn from his hand. A section of the heel was neatly carved off. He saw it then, a brief sparkle ahead and to his right.

The needlelike stream was jetting against the mounted base of the compact steam turbine that drove the DSMV’s huge traction belts. The thick titanium mount withstood the concentrated power of the leak’s spurt, but its tough surface had already been etched and pitted from the narrow onslaught.

Pitt had isolated the problem, but it was far from solved. No caulking, no sealant or tape could stop a spewing jet with power to cut through metal if given enough time. He stood and edged around the turbine to a tool and spare parts cabinet. He studied the interior for a brief instant and then pulled out a length of high-pressure replacement pipe for the steam generator. Next he retrieved a heavy sledge-type hammer.

The water had risen to half a meter by the time he was ready. His makeshift scheme just had to work. If not, then all hope was gone and there was nothing he and Plunkett could do but wait to either drown or be crushed by the incoming pressure.

Slowly, with infinite caution, he reached out with the pipe in one hand and the hammer in the other. He lay poised in the rapidly rising water, inhaled a deep breath, held it a moment, and then exhaled. Simultaneously he shoved one end of the pipe over the entry hole, careful to aim the opposite end away from him, and immediately jammed it against the angled slope of the thick bulkhead shield separating the turbine and reactor compartments. Furiously he hammered the lower end of the pipe up the angle until it was wedged tight and only a fine spray escaped from both top and bottom.

His jury-rigged stopgap may have been clever, but it wasn’t perfect. The wedged pipe had slowed the incoming flood to a tiny spurt, enough to get them to the summit of the guyot, hopefully, but it was not a permanent solution. It was only a matter of hours before the entry hole enlarged itself or the pipe split under the laserlike force.