Adventure deep at Silver Island

First time past twenty metres. Wall dive. Target depth twenty-one metres. Bottom time twenty-five minutes. Turnaround pressure one hundred and twenty bar. Safety stop at five metres, three minutes, then back to the boat.

The brief from Mr. Huy was three sentences I wrote on a slate. Everything slows at depth, including your judgment. The gauges are not optional, they are the dive. The story you tell yourself about how good the dive is, is the story you cannot trust.

I had a written checklist in the dry bag on the boat. I read it again before I got into the water. The checklist did not have a single thing on it I did not already know. The point was not the contents. The point was reading them again at the only time it was still cheap.

The descent was clean. I hit eighteen metres in two minutes and dropped the last three metres at a slower pace, equalising in pulses. At twenty-one metres, the wall opened out below me into a depth I had not been in before. The blue at depth is a different blue than the blue at fifteen metres. It is heavier. It is the colour the ocean looks when the ocean has stopped being shallow.

The first thing I noticed was that my breathing was slower without my doing anything. I had read that this happens. I had not felt it. The body becomes more efficient at depth, and the efficiency feels like calm. It is not calm. It is a physiological state that resembles calm closely enough to be confused with it. I caught the confusion early because Mr. Huy tapped his regulator and gestured at my SPG. The gesture meant: check the gauge anyway.

The second thing I noticed was the way time stretched. Five minutes felt like one minute. The wall was full of small things to look at. There was a banded coral shrimp in a crevice. There was a stonefish on a ledge that I did not see until Mr. Huy pointed it out. There was a school of fusiliers above us that moved the way schools of fusiliers move, which is the thing every diver wants to see and the thing every diver thinks they will not get to see on their first deep dive.

I checked my SPG every two minutes because I had told myself before the descent that I would. At minute eighteen, I read one hundred and twenty bar. Turnaround pressure. The plan had been twenty-five minutes of bottom time. I had eighteen. I had seven minutes of plan I would not get to spend.

I made the call. I signalled the ascent. Mr. Huy nodded once and matched my pace.

The slip was the temptation to round.

I had one hundred and twenty bar on the nose. I had eighteen minutes of bottom time. The number was not slightly above the rule and not slightly below. It was exactly at the rule. Which meant that if I had told myself I had read one hundred and twenty-five, or that the SPG was a little optimistic, or that I had been a touch conservative at depth, I could have stayed for three or four more minutes and never crossed the line.

I felt that calculation happen in my head. It was three seconds long. The output of the calculation was that I went up anyway. The input of the calculation was the slip.

The slip is that I let the calculation start. The rule was one hundred and twenty bar. The SPG read one hundred and twenty bar. There is no calculation. The next motion is the ascent signal. The slip is that I gave the calculation three seconds of room, and three seconds at depth is the rest of my career, because the next dive the SPG will be at one hundred and twenty-two and the calculation will get four seconds, and the dive after that it will be one hundred and twenty-five and five seconds, and at some point the calculation will win and I will not even notice the moment it did, because the slope from one hundred and twenty exactly to a slow violation that becomes a habit is short and downhill.

The first deep dive taught me what the gauges are actually for. They are not there to tell me information. They are there to settle an argument that I should not have been having in the first place. The argument is the dangerous part of the dive. The gauge is the way I do not get to have the argument.

The body felt calm at depth. The breath felt slow. The conditions were perfect. Mr. Huy was right next to me. The fusiliers were above. None of these things matter for the rule. The rule was one hundred and twenty bar. I went up at one hundred and twenty bar. That is the dive. Everything else is photography.