Poseidon's Arrow

Dirk had to wait for her to stick her head above water before replying. “I’m not ready to play Dr. Kildare just yet,” he said, forcing a grin. “Wait right here.”

Before she knew it, he had opened the hatch and swum out of the submersible, leaving her trapped and alone in the dark.

46

SUMMER COULD NOT REMEMBER WHEN SHE HAD FELT so terrified. Trapped alone in the blackness of the ocean depths, she felt her heart racing. Once the submersible’s interior had flooded, Dirk had opened the hatch and swum away with the waterproof flashlight. She shivered uncontrollably, from the fear and the cold water, as her fingers and ears turned numb.

But the worst was the near silence. Crouched on the overturned seat, she could hear only the pounding of her heart and the sporadic sucking and gurgling of her breath through the regulator. As her mind began inventorying her fears, the act of breathing rose to the top of the list. Her air consumption at the current depth was much higher than near the surface. The cylinder might provide her only a few minutes of air. But what if it hadn’t been filled to capacity? A devilish voice in her head asked whether each breath from the tank would be her last.

She squeezed her eyes shut and tried to relax, extending the time between inhalations and forcing a steady breathing rhythm. When she felt her heartbeat slow, she pried open her eyes, but still found herself surrounded by a cloak of blackness. Never prone to claustrophobia, she still couldn’t help feeling like she was locked in a very small, very dark closet.

She began to wonder if her brother had changed his mind and headed for the surface—then she saw a dull glow outside the canopy. The light grew brighter until she could make out the flashlight’s beam as it drew closer. Though it seemed he had been gone for hours, it had been only a few minutes.

When Dirk climbed through the hatch a second later, she saw he was wielding a five-foot steel pole with a brass ball affixed to one end: the severed flagpole from the shipwreck. The submersible had struck bottom alongside the wreck, which Dirk had recognized through the bubble.

Dirk crawled forward and wedged the pole between the seat frame and the housing that clamped against Summer’s foot. Grabbing the opposite end, he pulled like an Olympic oarsman. The metal supporting the seat buckled immediately, allowing Summer to free her foot. She gave Dirk a hug, then signaled “Ascend” with an upraised thumb.

Dirk shined the light at the open hatch and gave her a shove. They had spent a dangerous amount of time at a depth close to three hundred feet and knew not to linger.

Summer waited outside the submersible for him, and they linked arms and began their ascent together. They kicked in a slow, measured pace, using their rising exhaust bubbles as a speedometer. Ascending too quickly would be a surefire recipe for the bends, and Dirk made sure they lagged behind the fast-rising bubbles.

It seemed to take forever. Summer was glad for the exertion, which slightly warmed her frozen bones, but her mind still wanted to play tricks on her, telling her they weren’t actually ascending or that they were actually falling back to the depths. It was the cold, she told herself, making her senses numb along with her extremities. She clung to Dirk, who moved like a robot, seemingly immune to the cold and dark.

At a depth of one hundred and fifty feet, the waters noticeably lightened as the surface light began to penetrate the deep. At one-twenty, they passed through a thermocline, and the water temperature warmed. And at eighty feet, Dirk ran out of air.

He wasn’t surprised. Because of his exerted swim to the wreck and back, he knew his air would fail before Summer’s. Drawing his hand across his throat to signal Summer, he jettisoned his tank and regulator. She passed her regulator over, and they began alternating breaths, unconsciously kicking more quickly toward the surface.

Dirk looked up and saw a faint ripple of silver far above their heads. They were now close enough to reach the surface if Summer’s air failed. But now they had another problem.

Exposure to the pressurized depths allows tiny nitrogen bubbles to form in the body’s tissue. If not allowed to dissipate via a gentle reduction in pressure, the gas bubbles can lodge in the body, creating the agonizing and sometimes fatal malady of the bends.

Dirk estimated they had spent close to fifteen minutes on the seafloor. The Navy Dive Tables called for multiple decompression stops, but they had no such luxury. They ascended to what Dirk guessed was about twenty feet and then held their position. Their natural buoyancy and the swift current made it a challenge, but he kept his eye on the surface and fought to keep them in place.

They milked the tank for another ten minutes before Summer spat the regulator out of her mouth and pointed up. They both shot to the surface, exhaling as they swam.

Their heads broke the surface amid a choppy sea dotted with whitecaps. The sun had already vanished, leaving the sky a darkening shade of pewter. The combined effects would render them almost invisible to a passing ship, even one that was searching for them. Yet that wasn’t first on Summer’s mind.

Sucking in a deep breath, Summer turned to her brother. “A flagpole?”

“Best I could do, under the circumstances. How’s the foot?”

“The foot’s okay, but I have a painful cramp in my ankle.” She shot him a concerned gaze. “I don’t think we came anywhere close to covering our deco time.”

Dirk shook his head. “No, we were well short. Do you feel any tingling anywhere?”

“I’m too numb to feel much of anything.”

“We might be sleeping in the Alexandria’s decompression chamber tonight.” He sca

They finally spotted the NUMA vessel far to the west. The dark band of the Madagascar shoreline was visible a bit closer, to the north.

“The Alexandria is up current,” Dirk said. “No way we can swim to her.”

“They’ve probably swept by already and are backtracking with a sonar survey to locate the submersible. We’ll have drifted to Australia by the time they get back this way.”

“Then to shore it is,” Dirk said. “Are you up for the swim?”

“Do I have a choice?”

She eyed the coastline, put her face in the water, and started swimming. They were both excellent swimmers in fit shape. Under normal circumstances, the open-water swim to shore would have been little more than a tiring challenge. But the mental strain of their escape from the submersible, combined with their cold-water exposure, turned it into a life-or-death task. Fatigue struck both swimmers almost immediately. Summer couldn’t believe how quickly her arms and legs felt like they had turned to lead.

The turbulent seas didn’t help. The waves frequently tossed them about and filled their mouths with salt water. Swimming toward the coastline meant they were working across the current. Each stroke to shore carried them a nearly equal distance to the east, and that much farther from the Alexandria.

The pair swam side by side, stopping to rest every ten minutes. While treading water, Dirk would fish the flashlight out of his pocket and waggle its beam at the research ship. On their third rest, the light slipped from his numb fingers, dropping into the depths like a candle down a well. By now, the NUMA ship appeared even farther away, just an occasional dancing light on the horizon.

Dirk turned toward Summer. “C’mon, less than a mile to go.”

She willed her limbs forward, but they had a mind of their own. A deep pain began burning in her left leg, then gradually vanished, along with all feeling in the limb. She began resting at shorter and shorter intervals, and Dirk could see she was begi