Chapter 16: The Ascent Begins

At 08:00 on day twenty-two, the pressure began to fall.

The hiss was different from the blow-down hiss. The blow-down hiss had been the sound of gas entering — helium flooding the chamber, the pressure building, the atmosphere thickening. The decompression hiss was the sound of gas leaving — the chamber's atmosphere venting through the exhaust valve, the pressure dropping, the helium escaping from the chamber the way it was simultaneously escaping from the divers' tissues, the chamber and the bodies decompressing in parallel, the system releasing what it had held.

The rate was slow. Imperceptibly slow. The decompression schedule specified a rate that varied with the depth — faster at the deeper stages, where the body's tissues were less saturated and the gradient for gas release was steeper, and slower at the shallower stages, where the tissues were approaching surface saturation and the margin for error was narrower. At the start, the rate was approximately three metres per hour. By the end, it would be less than one metre per hour. The total decompression from 150 metres to the surface would take approximately 120 hours — five days.

Five days. One hundred and twenty hours. Seven thousand two hundred minutes. In each of those minutes, the pressure in the chamber would drop by a fraction of a millibar, a fraction so small that no gauge could display it in real time, the change detectable only by comparing readings taken hours apart, the way the growth of a child is detectable only by comparing measurements taken months apart — the change happening continuously but below the threshold of perception, the body changing without knowing it is changing.

Kwame sat on his bunk and felt nothing. The decompression had begun, according to the gauge and the schedule and Sarah's announcement, but the body could not feel it — could not detect the difference between 15.2 bar and 15.15 bar, could not sense the fractional reduction in the atmosphere's density, could not register the infinitesimal decrease in the pressure on the eardrums and the sinuses and the chest. The body was at depth, and the body did not know it was ascending.

But the body was ascending. The helium in his blood was beginning to diffuse — the partial pressure of helium in his tissues fractionally higher than the partial pressure of helium in the chamber atmosphere, the gradient driving the gas out of the blood and into the lungs, the lungs exhaling the helium into the chamber, the chamber exhausting the helium to the surface. The process was molecular. It happened at the level of individual gas molecules crossing cell membranes, negotiating the boundary between the dissolved state and the gaseous state, each molecule making its individual transition from the inside to the outside.

The decompression was, at the molecular level, a release. A letting go. A surrender of the gas that the body had held for twenty-one days, the inert cargo that the tissues had accepted under pressure and that the tissues were now, gradually, relinquishing.

Kwame thought about letting go. He had been thinking about letting go since the letter, since the five words in the notebook — I am thinking about going home — since the full letter he had written and sent through the medical lock, the words that were now somewhere between Aberdeen and Accra, crossing the distance, carrying his intention.

Letting go was not the same as leaving. Letting go was what happened after the leaving had already been committed to, the process by which the body and the mind released the accumulated pressure of the state they had been in. The leaving was the decision. The letting go was the physics.

The chamber's decompression was the physics of leaving the depth. The molecules leaving the tissues. The pressure leaving the chamber. The numbers on the gauge descending. The slow, controlled, patient release.

And Kwame's own decompression — the emotional decompression from six years of distance — was also physics, of a sort. The accumulated pressure of the unsaid and the undone and the unvisited, stored in his tissues the way the helium was stored, compressed into his being by the sustained exposure to the depth of absence, the pressure of guilt, the atmosphere of avoidance. This pressure had been building for six years, and the release would take time, would require patience, would demand the same controlled, gradual approach that the physical decompression demanded.

You could not surface too quickly. The lesson of decompression was the lesson of patience — the understanding that the body could not tolerate a rapid change in pressure, that the gas dissolved in the tissues would form bubbles if the pressure dropped too fast, and that the bubbles would lodge in the joints and the blood vessels and the brain and cause pain and damage and, in the worst cases, death. The bends. The decompression sickness. The price of impatience.

Kwame would not be impatient. He would decompress. He would take the time. He would allow the pressure to release at the rate the physics required — not faster, not slower, but at the rate that the body could tolerate, the rate at which the gas could diffuse safely, the rate at which the transition from depth to surface could be made without damage.

The first hours of decompression were indistinguishable from the last hours of saturation. The chamber was the same. The atmosphere was the same — or nearly the same, the helium fraction fractionally lower, the oxygen fraction fractionally higher, the adjustments made by the life support system to maintain the oxygen partial pressure as the total pressure dropped. The men were the same — Mac reading, Sean talking, Tomasz puzzling, Davy counting, Fraser tidying. The food was the same. The tea was the same. The fluorescent light was the same.

But the knowledge was different. The knowledge that the pressure was falling, however imperceptibly, changed the quality of the time. The time in saturation had been a steady state — a plateau, a flat line on the pressure chart, the days at 15.2 bar stretching out identically, each one the same pressure as the last, the sameness a kind of stasis. The time in decompression was a gradient — a slope, a line descending on the chart, each hour at a slightly lower pressure than the last, the descent a direction, a trajectory, a movement toward a destination.

The destination was the surface. The destination was one atmosphere. The destination was the world.

Kwame sat at the table and read Achebe. He was near the end of Arrow of God — the novel's arc curving toward its conclusion, Ezeulu's authority challenged and his world changing, the old order giving way to the new in the way that all old orders gave way, not with a single decisive moment but with the accumulation of small shifts, each one insufficient to constitute a change but collectively amounting to a transformation.

He read the passage where Ezeulu's son Oduche sealed the sacred python in the box — the act of containment, the living thing trapped inside the dead thing, the sacred inside the profane, the wild inside the domestic. The python was Ezeulu's authority, Kwame thought. The python was the thing that could not be contained but that was contained anyway, the thing that was too large for the box but that was forced into the box by the son who had been sent to the mission school and who had learned, from the missionaries, that the sacred could be contained, that the authority of the old could be boxed and sealed and replaced by the authority of the new.

Kwame had been sent to a school too. Not a mission school — a welding school, secular, technical, concerned not with the sacred but with the metallurgical. But the sending had the same structure: the son dispatched from the old world to the new, the son acquiring the knowledge and the tools and the language of the new world, the son returning — or not returning — to the old world with the knowledge that the old world could not fully absorb, the skills that the old world did not need, the language that the old world did not speak.

He had been sent, and he had been changed by the sending, and the change was the thing that made the return difficult — not the logistics, not the schedule, not the cost, but the change itself, the fact that the Kwame who would return to Osu was not the Kwame who had left, and that the difference between them was not a matter of years or distance but of pressure, of the sustained compression of a life lived at depth, in the between, in the space where the old world and the new world did not meet.

But they would meet. They would have to meet. The decompression was the meeting — the slow, controlled bringing together of the two pressures, the depth pressure and the surface pressure, the between and the home, the son who had been changed and the mother who had been waiting.

At noon, Sarah read the numbers. Chamber pressure one-four-one metres. PPO2 zero-point-four bar. CO2 zero-point-three per cent. Temperature twenty-nine degrees. All parameters normal.

One hundred and forty-one metres. The pressure had dropped nine metres in four hours. Nine metres of ascent. Nine metres closer to the surface.

Kwame felt it now — not physically, the body still unable to detect the change at this rate, but psychologically, the knowledge of the descent working on him the way the knowledge of the dawn worked on a man who had been up all night, the anticipation of the light changing the quality of the dark.

Mac set down his Tom Clancy. He had reached page 203. He said: I've been thinking.

Kwame waited.

Mac said: About the house. About Linda wanting to sell. I've been thinking I should go in. Before she sells. I should go in one more time. See the kitchen. See the garden. Let the house know.

Let the house know what, Kwame said.

Mac said: That it can stop keeping her for me. That it can let go.

He picked up his tea. He drank. He set the mug down.

I've been holding that house closed, Mac said. Four years. Telling Linda not yet. Keeping the house sealed, pressurised, the heating on, the rooms full of my mum's things. I've been keeping the house at depth. And the house needs to decompress. The house needs to come back to the surface. The house needs to be a house again, not a — not a chamber. Not a sealed container full of an atmosphere that no one's breathing.

He looked at Kwame.

You made me think about it, Mac said. What you said. About the house holding the person. About going in and finding them everywhere. I've been afraid of that. I've been afraid of going in and finding her everywhere and having to — to accept that she's everywhere and she's nowhere. That the house is full of her and she's not in it. Both at the same time.

Kwame said: Both at the same time.

Mac said: Aye. Both at the same time. That's the hard part. Not the one or the other. Both.

They sat with this. The chamber hummed. The pressure dropped, imperceptibly, continuously, the system venting its stored atmosphere the way the men were venting their stored thoughts, the decompression working on both levels — the physical and the personal, the gas and the grief, the helium and the holding-on.

Kwame said: I am going home. To Accra. When we surface. I'm going to read the letters and call my brother and book a flight and go home.

Mac said: Good.

Kwame said: I wrote to my mother. I sent the letter through the lock. It's on its way.

Mac said: Good.

The word was enough. In the chamber, at depth, in the helium atmosphere, the word "good" carried the weight of an entire vocabulary of approval and support and encouragement, the word compressed by the pressure into something denser than its surface meaning, the way all words were denser at depth, the helium giving them a frequency that was higher but a gravity that was, paradoxically, greater.

The afternoon passed. The pressure continued to fall. By 18:00, the gauge read 132 metres — eighteen metres of decompression in ten hours. Eighteen metres closer to the surface. Eighteen metres of helium released from the chamber and from the bodies of six men, the gas diffusing out of the blood and the fat and the bone and the brain, the molecules negotiating their exit, each one crossing the membrane between the dissolved state and the free state, each one a small release, a small letting go.

Kwame noticed the first physical change at 125 metres, on the morning of day twenty-three. His voice was different. Not dramatically — the helium was still the dominant component of the atmosphere, the voice still high and distorted — but fractionally, the pitch a semitone lower, the resonance a shade deeper, the words arriving at his own ears with a quality that was, by a margin almost too small to detect, closer to his natural voice.

The voice was returning. The real voice, the surface voice, the deep voice that his mother would recognise, was beginning to emerge from beneath the helium distortion, the way a shape emerged from beneath marine growth when you scraped it — gradually, the original surface appearing, the paint or the steel or the identification plate revealed by the removal of the accumulated overlay.

He noticed it. Mac noticed it. The others noticed it, each man hearing his own voice changing and hearing the others' voices changing, the collective voice of the chamber shifting downward, the helium choir descending toward the surface register, the pitch dropping with the pressure, the sounds of the chamber gradually, over the five days of decompression, returning to the sounds of the world.

Day twenty-three. Day twenty-four. The pressure fell. The voices deepened. The food began to taste like food again — the flavour compounds, suppressed by the dense helium atmosphere, emerging as the atmosphere thinned, the curry tasting like curry, the fish tasting like fish, the tea tasting like tea, each meal a small revelation, a small return, the senses recalibrating, the body's instruments coming back online as the pressure released.

The sleep changed. The vivid dreams of saturation gave way to the shallow, restless sleep of decompression — the body adjusting to the changing pressure, the tissues releasing gas, the joints occasionally aching as small bubbles formed and dissolved in the synovial fluid, the aches not painful enough to require treatment but present enough to disturb the sleep, the body reminding the mind that the decompression was not a passive process but an active one, a negotiation between the body and the physics, the tissues letting go of the gas they had held and the gas resisting the letting go with the small protests of a substance that had found a place and was reluctant to leave it.

Kwame lay in his bunk at night and felt the aches — a dull soreness in his right shoulder, a twinge in his left knee, the minor discomforts of a body releasing its stored helium through the controlled process of decompression. The aches were normal. The aches were expected. The aches were the body's way of saying: I am changing. I am releasing. I am letting go.

He thought about his mother's knees. The arthritis. The twelve steps. The aching that she carried every day, not the aching of decompression but the aching of time, the body's accumulated wear, the joints protesting the years of use, the climbing and the carrying and the standing at the market and the kneeling in the kitchen and the ten thousand days of movement that had worn the cartilage and inflamed the tissue and produced the pain that she managed with ibuprofen and the railing and the refusal to move the bedroom downstairs.

His aches would pass. Five days and the decompression would be complete and the aches would resolve and his body would be at surface pressure and the helium would be gone. His mother's aches would not pass. His mother's aches were the aches of a decompression that would not complete, a pressure that would not fully release, the body's gradual acknowledgment of its own limits.

He wanted to be there. He wanted to be at the bottom of the twelve steps when she came down in the morning. He wanted to offer his arm. He wanted to climb the steps with her, slowly, one step at a time, his hand on her elbow, his presence beside her, the son accompanying the mother the way the bellman accompanied the diver — not doing the work for them but being there, being present, being the support that made the difficult crossing possible.

This was what Yaw did. This was what Yaw had been doing for years. This was the daily diving that Yaw performed — the descent into the demands of care, the lock-out into the needs of the household, the hours at the depth of presence. Yaw's diving was not at 150 metres and fifteen atmospheres. Yaw's diving was at the kitchen table and the pharmacy counter and the clinic waiting room, and the depth was not measured in metres but in years, and the pressure was not measured in bar but in the weight of being there, being present, being the son who stayed.

Kwame owed Yaw the acknowledgment of this. The letter to his mother had said it — I owe Yaw an apology — and the apology was not for the leaving, which had been necessary, which had been the right decision for Kwame's life and career, but for the silence about the staying, for the failure to recognise that Yaw's staying was as deliberate and as costly as Kwame's leaving, that the present son worked as hard as the absent son, that the daily dive was as demanding as the deep dive.

Day twenty-four. 102 metres. The pressure was below 100 metres for the first time in twenty-two days. The number on the gauge — 102, then 99, then 97 — carried a significance that was psychological rather than physical, the crossing of the hundred-metre line a threshold, a marker, a point at which the diver could say: I am less than a hundred metres from the surface. I am closer to the air than to the depth. I am more than halfway home.

The helium was thinning. The atmosphere was changing. Nitrogen was being reintroduced to the breathing mix — the life support system adding nitrogen to the chamber atmosphere as the pressure dropped, the heliox gradually becoming trimix, the three-gas mixture of helium, nitrogen, and oxygen that was breathed during the transition from depth to surface, the body's tissues beginning to absorb the nitrogen that would replace the helium, the swap happening at the molecular level, each nitrogen molecule taking the place of a helium molecule in the blood and the tissues, the body's chemistry transitioning from the deep-dive state to the surface state.

The voices continued to deepen. Kwame's voice at 97 metres was recognisably his voice — not yet the full baritone of the surface, but close, the helium distortion fading, the natural resonance returning, the words arriving at his own ears with a familiarity that was, after twenty-two days, almost startling.

He spoke, and the voice he heard was almost his own.

He would be home soon. Not in Accra — in himself. In his own voice, his own body, his own pressure. The decompression was returning him not just to the surface but to the person he was at the surface, the person his mother would recognise, the person whose voice she carried in her memory, the deep voice, the Kwame voice, the voice she was waiting to hear.

Three more days. Seventy-two more hours. The pressure falling, the voice deepening, the body releasing, the numbers descending toward one.

Toward the surface. Toward the air. Toward the world.

Toward home.