Treasure of Khan

Dirk glanced at his dive watch as he wrestled the airlift over a few inches. Only fifteen minutes to go till the end of the shift, then a break from the monotonous work. Progress was slower than he had hoped, but he had still uncovered a rough square about six feet across. The encrusted wood was thick but flat, consistent with the shape of a ship's rudder. Only the size was a little perplexing. Dahlgren's probe marks had encompassed an object nearly twenty feet long, an enormous dimension for a sailing ship rudder.

Following the ascent of his air bubbles as they rose to the surface, he gazed again at the undersides of the large black ship moored next to the barge. He and Dahlgren had heard the rumble of the ship's engines underwater as it drew near and they watched with curiosity as the dark shape brazenly drew alongside the barge. They had watched the positioning thrusters engaged and felt a slight assurance that the fool wasn't going to drop anchor on them. Another well-financed video documentary group, Dirk surmised. There would no doubt be an array of underwater photographers descending on them shortly.

Hooray, he thought sarcastically.

He shook off the a

A few yards away, Dahlgren was driving his probe into the sand. Out of the corner of his eye, Dirk noticed him suddenly rise off the bottom. Something about the movement didn't seem right and Dirk looked over to see that his instincts were right. Dahlgren had let go of the probe and had his hands wrapped around his faceplate and air line, while his legs hung loose beneath him. He was being yanked off the bottom, Dirk realized, like a puppet on a string.

He had no time to react, for an instant later the airlift was ripped from his own hands, sailing off through the water in the direction of Dahlgren. Dirk looked up just in time to see his own air line pull taut in the water and then jerk him up off the seafloor.

"What the ..." he started to mouth, but the words fell away as he tried to draw a breath of air. He inhaled a slight puff and then there was nothing. The compressor supplying the air lines had been cut off, too. Like Dahlgren, he found himself grabbing hold of the air line to control his movements and not rip the co

But Dirk didn't panic. He had spent the better part of his life scuba diving. Technical failures underwater were nothing new to him. He had sucked a tank of air dry on shallow-water dives many times. The key to surviving an emergency, underwater or elsewhere, he told himself, was to remain calm and think logically.

Air was the first necessity. His natural inclination was to kick to the surface, but that wasn't necessary.

While working on surface-supplied air, the divers all carried a small emergency bottle of air. Slightly larger than a thermos, the thirteen-cubic-foot bailout bottle, called a "pony tank," provided about ten minutes of air. Dirk let go of the air line with one hand and reached under his left arm, where the bottle was attached to his buoyancy compensator. Twisting the valve on the top of the tank, he immediately drew in a breath of air through the regulator. After a couple of deep draws, he could feel his heart begin to slow its racing beat.

His thoughts ran to Dahlgren, who was on the shared line of surface air. Thirty feet ahead, he saw a purge of exhaust bubbles rise from Dahlgren's helmet and knew that he was breathing off his emergency air as well. The dangling airlift had ventured over toward Dahlgren and was gyrating in the water close behind him. The airlift pipe was being dragged by its flexible outlet hose secured to the barge, which created an elastic springing action like a rubber band. The hose would stretch under the drag of the water-filled tube, then snap back, whipping the tube forcefully through the water. Dirk saw that the tube was pulled taut in a precarious position behind Dahlgren and he waved to get his friend's attention. The Texan was busy pulling himself up the air line and didn't see the airlift or Dirk's warning. A second later, the outstretched tube burst forward, launching straight toward Dahlgren. To Dirk's horror, the tube shot up like an arrow and struck the back of Dahlgren's head just beneath his dive helmet. As the airlift fluttered off, Dahlgren's body went limp.

Dirk cursed to himself as he felt his heart race faster again. He noticed that the seafloor had dropped away beneath them and that they were being pulled more forcefully through the water. On the surface, an offshore breeze had joined forces with the island currents to push the stubby barge along at over four knots. Under the waves, Dirk wondered why in blazes the barge was drifting and where Summer was.

Then he turned toward Dahlgren. There was no thought of surfacing yet. He had to reach Dahlgren and make sure he was still breathing.

With a frantic determination, Dirk began reeling himself up the air line to close in on Dahlgren. His tired arms ached in pain with each pull, made harder by the thirty-five-pound weight belt strapped around his midsection. He didn't dare jettison the belt yet, as he needed to stay at the same submerged depth as his friend.

Pulling himself up like an underwater mountaineer, he clawed his way to within ten feet of Dahlgren when his old nemesis reappeared. The dancing airlift came rushing toward him, swinging past just out of arm's reach. The big tube swung toward Dahlgren, flexed a moment, then reversed direction and bounded back. This time, Dirk stuck out an arm and caught hold of the tube as it swung by. The heavy mass of the water-filled tube nearly jerked him out of his fins as he straddled his legs around it and bounced through the water. Riding it like a bucking bronco, he carefully shimmied up to the top of the tube, where it was clasped to the thick rubber hose. Pulling out a small dive knife that was strapped to his leg, Dirk lunged at the hose with the blade and began sawing through it. The tube whipped violently beneath him as he muscled the knife through to sever the hose. The heavy plastic tube snapped away with the last cut and sank to the depths as Dirk slid off and gave it a farewell kick.

Free of the mad battering ram, Dirk turned his attention back to Dahlgren. Dirk's fight to rid himself of the airlift had caused him to lose his place on the air line and he found himself trailing Dahlgren by thirty feet again. His friend looked like a wet mop, towed through the water by the line from his neck. With his tired arms stinging, Dirk pulled himself up the line again, fighting foot by foot until he was even with Dahlgren. He coiled his own air line around his waist in a bowline knot, then kicked and swam his way over to his friend. Reaching over and grabbing Dahlgren's BC, Dirk pulled himself up and peered into his face mask.

Dahlgren was unconscious with his eyes closed. He was breathing lightly, though, as evidenced by a small stream of exhaust bubbles that floated out of his regulator every few seconds. Grabbing Dahlgren with one hand, Dirk reached down and unbuckled his own weight belt, then reached up to his buoyancy compensator and hit the button on the inflation hose. What little air was left in his emergency pony bottle surged into his vest, filling it half full before ru