Fifteen Metres Underwater: The Race the Stopwatch Cannot See

At five forty in the morning, only two lanes of the 50-metre pool in Nha Trang were still moving. A fourteen-year-old boy had just pushed off the wall, both arms extended straight behind his ears, and for the next ten seconds or so he did not surface. I stood at the pool edge, phone set to slow motion, and I counted. One, two, three… nine dolphin kicks before his face broke the surface exactly at the fifteen-metre mark. The coach standing beside me said nothing. He simply nodded and wrote a number in his notebook.

That number will never appear on any scoreboard. No scoreboard in Vietnam records it. And that is why I am starting this piece from a morning with no spectators, no medals, and no applause.

The 2026 World Cup taught me a lesson I still carry every time I sit down to write. I was nineteen, interning at a local radio station, and I mispronounced the name Kylian Mbappé three times in a row on air. Social media tore me apart. I spent a month rewatching every France match, recording the voices of international commentators, checking UEFA's phonetic guide. From one mispronunciation at a World Cup, I learned that football does not begin with the foot, but with the ear. Ten years later, sitting at the edge of a swimming pool just before six in the morning counting a child's kick rhythm, I understood something similar: swimming does not begin with the arms. It begins in the water nobody films.

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Context: A sport quietly restructuring itself

After Paris 2026, the swimming world entered a new four-year cycle with a visibly shifted map of power. Leon Marchand left Paris with four individual gold medals — 200m butterfly, 200m breaststroke, 200m individual medley and 400m individual medley — a haul that placed him in a very narrow group of swimmers who have won four individual titles at a single Olympic Games. Katie Ledecky continued to accumulate results and became the most decorated female swimmer in Olympic history. Summer McIntosh, still a teenager, broke the women's 400m individual medley world record. Pan Zhanle broke the 100m freestyle world record with 46.40 seconds on a relay lead-off leg.

Running alongside that current of results is another current that is far less discussed: the movement of coaches, of training centres, of athletes changing colours. Swimming does not have a transfer window in the football sense. But it has an equivalent, and that equivalent operates far more harshly. A national team head coach moving to a US collegiate programme can pull five athletes with him in a single season. A new training centre opening in Southeast Asia can shift an entire generation. And in Vietnam, we are living through exactly that kind of shift, largely without the audience noticing, because it is not as loud as a transfer deal and nobody is publishing exclusives about it.

Vietnamese swimming in this cycle faces three overlapping questions. The first is generational: the cohort that delivered results at past SEA Games is entering the final phase of its career curve, while the cohort behind it has yet to establish who its pillars are. The second is infrastructural: the number of 50-metre pools serving high-performance training and competition in Vietnam remains very low relative to demand, and that leaves a direct mark on athletes' technique. The third is methodological: what are we measuring, and what are we overlooking?

The third question is the one I care about most, and the one I believe is being answered wrongly in a great many places.

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Core: A stroke-by-stroke map of power

Freestyle: a war of hundredths

In the men's 100m freestyle, Pan Zhanle's world record of 46.40 seconds, set at Paris 2026, is an emblematic marker. Over the roughly twenty years before it, the record had crept from around 47.8 down to 46.9, then pushed to 46.8, then to 46.4. Every tenth of a second shaved off represents an entire training system rewriting itself.

What separates swimmers in the 100m is not the arms. It is the distribution of speed across the first twenty-five metres and the last twenty-five metres. I have spent many evenings clicking a stopwatch through 25-metre splits of major finals, and the pattern repeats often enough that I trust it: champions are not the swimmers with the fastest opening split, but the ones who decelerate least in the third and fourth segments. Swimming fast is a matter of muscle. Holding speed once lactate has flooded the tissue is a matter of the central nervous system and of how breathing rhythm is allocated.

In the women's 200m freestyle, Mollie O'Callaghan has pushed the world record into the 1:52 range, territory once considered unthinkable for women. Ariarne Titmus holds the women's 400m freestyle world record at 3:55.38. Both numbers tell the same story: middle-distance events on the women's side are evolving faster than sprint events, and that evolution comes from aerobic training volume built correctly during the teenage years.

In Vietnam, we have almost no swimmers capable of swimming the 200m freestyle at continental level. Nguyễn Thị Ánh Viên did it at her peak, but that was an exceptional individual rather than the output of a system producing swimmers in numbers. Here is the point I want to stress: a swimming nation cannot survive on one genius. It survives only when the second and third tiers are thick enough to push the first tier upward.

Butterfly: where technique decides before fitness speaks

The men's 200m butterfly is among the cruellest events in the sport. Kristof Milak held the world record at 1:50.34, and Leon Marchand took over as Olympic champion in the event. But looking at results sheets, one detail is routinely missed: the gap between gold and bronze in the 200m butterfly is usually created in the third length.

The third length of a 200m butterfly is where things break. The first two lengths are strength. The fourth is will. The third is pure technique — hip height on the recovery, hand entry angle, and how long the head stays in a neutral position. I have counted this while rewatching finals: swimmers whose hips drop too early in the third length lose roughly eight tenths to 1.2 seconds in the fourth, and no amount of willpower compensates for that number.

In butterfly, technique is not the decorative part of fitness. It is a precondition. A butterfly swimmer with good technique and average fitness will beat one with good fitness and average technique at every distance from 200m upward.

Backstroke: the underwater revolution

Kaylee McKeown and Regan Smith have together pushed women's 100m and 200m backstroke world records into territory I needed a moment to believe was real. Regan Smith set the 100m backstroke world record at 57.13. Hubert Kos delivered Hungary's gold in the men's 200m backstroke in Paris.

What do all those names share? They are all freakishly good at the underwater phase.

In backstroke, the rules allow a swimmer to stay underwater for up to fifteen metres after leaving the wall. Most amateurs surface after four to six metres. Elite swimmers surface at twelve to fifteen. That distance differential, multiplied by the number of turns in a 200m race, produces a gap that can reach two seconds.

Two seconds over 200m is the difference between a spot in an Olympic final and a ticket home after the heats. And those two seconds are created somewhere the television audience barely sees, because underwater cameras are placed at a few fixed positions and most broadcast time goes to surface angles.

Breaststroke: a problem of mechanics against the current

Adam Peaty once dragged the men's 100m breaststroke below 57 seconds, a milestone the analytical world took years to digest. Breaststroke is the only stroke where drag increases precisely when the swimmer needs speed most — when the legs are drawing up to prepare for the kick.

The solution lies in a very small detail: the timing of the leg recovery. Recover too early and you lose kick power. Recover too late and drag eats the speed you just generated. The ideal recovery window at world level sits within roughly two tenths of a second, and it varies by athlete depending on leg length, hip joint flexibility and glute strength.

I once sat clicking a stopwatch for a Vietnamese male breaststroke swimmer during a session in Nha Trang. His leg recovery was about four tenths of a second slower than the international benchmark for the same distance. Multiplied across forty strokes in a 100m race, that is sixteen seconds. The body does not accumulate quite that linearly, of course, but it shows the scale of the problem.

Individual medley: where the world map is being redrawn

The 400m individual medley is the event Leon Marchand dominated in Paris, and Summer McIntosh dominated on the women's side with a world record. The event demands mastery of four strokes, which raises a strategic question I will return to later: should a swimming nation develop specialists or multi-event athletes?

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Core (continued): The number at the fifteenth metre

I have tracked swimming and kept my own records for many years. My first notebook dates to 2026, when pools stood empty of spectators because of the pandemic and I switched to rewatching races on screen. I noted turn counts, underwater dolphin kick counts, stroke counts per length. None of those numbers appear on any official statistics page.

And what I found, over several years, is a rule so simple it is almost hard to believe: at distances of 100m and above, the difference between the world's best swimmers is created at three moments — the first fifteen metres after the start, the first fifteen metres after each turn, and the final two strokes before the wall.

Those three moments share one characteristic: they are not properly trained at most grassroots swimming centres, because they do not show up clearly on a normal training session's timing sheet.

A coach at a provincial pool can measure a pupil's 50m time. He cannot easily measure the distance at which the swimmer surfaces after a push-off, unless someone stands at the fifteen-metre mark to watch. And most pools in Vietnam have nobody standing at the fifteen-metre mark during training hours.

I once sat at the fifteen-metre mark for an entire two-hour session just to count. The session had about twelve young swimmers. Across roughly two hundred starts and turns, exactly eleven saw a swimmer surface at or beyond the fifteen-metre mark. Eleven out of two hundred.

This is what I call forgotten data. It sits there, obvious, measurable, and nobody measures it.

Pressing data does not lie, but it does whisper the name of a star still asleep. I wrote that line for football, but it applies to swimming almost unchanged.

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Core (continued): Nguyễn Huy Hoàng and the 800-metre problem

Among the current generation of Vietnamese swimmers, Nguyễn Huy Hoàng has the clearest position. He belongs to the distance group — 800m and 1500m freestyle — and has repeatedly delivered high placings at regional level.

But placed on the continental map, the picture becomes more complicated. In the men's 1500m freestyle, the technical gap between Asia's leading group and Southeast Asia's leading group is smaller than many assume. The gap in training volume is large.

Elite 1500m freestyle swimmers cover sixty to eighty kilometres per week during base-building phases. In Vietnam, that figure is usually considerably lower, and the reason is not the athlete's will. It is the schedule. A 50-metre pool shared among several training groups caps the number of high-performance hours an athlete can access.

Over distance events, infrastructure is not a supporting condition. Infrastructure is the central variable of performance.

One more thing I observed while rewatching Nguyễn Huy Hoàng's races: he distributes speed fairly evenly, with low variation between 100m segments. That is a rational tactic for an athlete with a strong aerobic base but limited capacity for a sudden late surge. The weakness of the model is that it does not create psychological pressure on opponents — and at continental level, psychological pressure is a real weapon.

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Core (continued): Trần Hưng Nguyên, Phạm Thanh Bảo and the second generation

Among the younger cohort, Trần Hưng Nguyên and Phạm Thanh Bảo are two notable names. Both have relatively solid technical foundations and have appeared at regional competitions.

What I want to discuss here is not individual assessment. It is the training structure behind them.

An elite swimmer needs four things: technique, fitness, competitive psychology and a competitive environment. The first three can be built fairly independently. The fourth cannot. A competitive environment exists only when at least five to seven athletes of comparable level train side by side every day.

In Vietnam, the number of swimmers meeting continental qualification standards in any given event can usually be counted on one hand. That means a talented young swimmer can spend most of a career training without ever having an equal in the next lane.

A lack of comparable rivals does not slow a swimmer down immediately. It slows them down over three to five years, and by the time it is noticed, it is too late to fix.

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Core (continued): The 25-metre pool and the trap of pretty records

A technical topic I believe is undervalued in Vietnam is the difference between a 25-metre pool and a 50-metre pool.

A 25-metre pool allows more turns over the same distance. Every turn generates new propulsion. That means a swimmer with excellent turning technique but a limited aerobic base can still post impressive times in a 25-metre pool. Moving to 50 metres halves the number of turns, and every aerobic weakness is exposed immediately.

In Vietnam, the majority of training pools are 25 metres. This produces a consequence I believe is far more serious than a shortage of medals: we are training and evaluating swimmers under a frame of reference that does not match the frame of reference they will compete in.

I once watched a young swimmer post excellent times in a 25-metre pool during an internal test, then struggle badly weeks later in a 50-metre pool. The coaching staff response was to increase training volume. That was the wrong response. The problem was not volume. The problem was that the test had measured the wrong thing.

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Core (continued): Taper and the art of unloading

In swimming, the unloading phase before a major meet — taper — is among the most misunderstood parts of the cycle.

The basic principle of taper is to reduce training volume while maintaining intensity, so that the body fully recovers and releases accumulated potential. Typical taper duration at world level ranges from ten days to three weeks, depending on distance and individual characteristics.

The most common taper error is to reduce both volume and intensity. The swimmer then loses feel for the water. Feel for the water is a neuromuscular skill, and it degrades quickly when not regularly activated.

A swimmer who tapers badly steps onto the blocks with a fresh body and unfamiliar hands. It is one of the worst sensations a swimmer can experience.

I once spoke with a coach who had worked abroad about this. He said something I recorded verbatim: "In Vietnam, we are good at making swimmers tired. We are not yet good at making swimmers fast."

Tired and fast are two different states. Training makes a swimmer tired. Taper makes a swimmer fast. If a training programme can only produce the first state, it has failed at the most important part.

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Contrarian angle: Specialisation or diversity

This is the section I want to give the most space to, because it runs against the intuition of most spectators and not a few sports administrators.

Intuition says: if you want a medal in an event, concentrate all resources on that event. Pick one event, pick one athlete, pour in money and time, and wait for the result.

I believe that intuition is wrong, at least in swimming, and wrong for three reasons.

The first concerns the spillover effects of technique. An athlete training across events — say combining freestyle and medley — develops several skill groups simultaneously. Backstroke turning technique improves freestyle turning technique. Butterfly breathing rhythm improves respiratory control in the closing stages of a 200m freestyle. Swimmers who train a single event from childhood often peak early and plateau early.

The second concerns risk. In a sport where the number of internationally qualified athletes can be counted on one hand, concentrating all resources on one individual is a high-risk strategy. A shoulder injury, a psychological plateau, a change in the coaching staff — any of these can erase years of investment.

The third, and the one I consider most important, concerns the internal competitive environment. A swimming nation with many multi-event athletes automatically creates competition across several events at once. A session with ten athletes swimming 200m medley carries a very different competitive charge from a session with two athletes swimming 100m breaststroke.

Diversity does not oppose specialisation. It is the ground in which specialisation can grow without snapping.

But I must add one thing to avoid being misread. Diversity does not mean scattering. A multi-event athlete still needs one flagship event, one in which he or she can compete at continental level. The other events serve as foundation, not as replacement.

The blind spot in the current Vietnamese approach, as I observe it, is that we classify athletes too early. A twelve-year-old who swims good butterfly gets channelled into a butterfly specialist track. But at twelve the body has not finished developing, and an athlete's optimal event at twenty can be entirely different.

Looking at the world map, I see very few elite swimmers who were single-event specialists from childhood. Leon Marchand started in medley and expanded to butterfly and breaststroke. Summer McIntosh swims from freestyle to medley to butterfly. Mollie O'Callaghan ranges from 100m to 200m freestyle and relays. The common pattern is expand then narrow, not narrow from the outset.

In Vietnam, our pattern is to narrow early, sometimes for a very practical reason: too few pools and too little training time. If a pool has only four hours a day for the high-performance group, splitting the group by specialist event makes organisational sense. But that organisational logic may be producing a performance disadvantage.

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Context: Vietnamese swimming and the unlabelled market of movement

In this cycle, what I observe in Vietnamese swimming is not a wave of transfers in the commercial sense. It is a wave of brainpower relocation.

Some experienced coaches who worked abroad are returning. Others go abroad to study and stay on to work in collegiate programmes. Private training centres in major cities are beginning to attract promising young swimmers, with training models closer to international standards.

This wave has two faces. The positive face is that it creates more pathways for a young swimmer. The negative face is that it can disperse resources and blur the national competition system.

The question I have set myself in this cycle is: if I want to follow a Vietnamese swimming talent from age twelve to age twenty, where do I go, whom do I meet, and what do I record?

I do not yet have a complete answer. But I know one thing: the data I need is not on any competition results sheet. It is in the notebooks of coaches standing at the pool edge at five forty in the morning, counting the kick rhythm of children who have never been on television.

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Contrarian angle (continued): Three myths to dismantle

I want to use this section to speak plainly about the three myths I encounter most often when writing about swimming.

The first myth: swimming is a sport for people with special physical gifts. That is partly true, but it is often used as an excuse not to invest in technique. Height and arm span are advantages, but those advantages only pay off when technique is good enough to exploit them. Many swimmers with ideal physiques never reach the top, because their technique wastes the very advantage they have.

The second myth: Vietnamese swimming cannot compete at continental level. That was true in many periods, but it is becoming a self-limiting belief. The gap between Southeast Asia's leading group and Asia's finalist group in some specific events is far smaller than the audience's general impression. Smaller does not mean easy to close, but at least it means the target is not absurd.

The third myth, and one I have encountered directly: women do not understand sports tactics. At a press conference after a women's football final at an Olympic Games, when I asked a coach about how a 4-2-3-1 shape operated in the second half, an older male reporter standing beside me whispered a line that embodied exactly that prejudice. I did not argue with him. That night I wrote a match report describing the team as a symphony, in which the attackers were the high notes and the midfield was the bass line holding the rhythm. That piece was read more widely than any purely technical analysis I have written about the same match.

When anger is converted into material, the anger becomes an asset. If it is converted only into a status update, it dissolves within twenty-four hours.

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Numbers and evidence: What I measured myself

I want to record a few verifiable facts here so readers have something to cross-check.

In the men's 100m freestyle, the current world record is 46.40 seconds, set by Pan Zhanle at the Paris 2026 Olympic Games on a relay lead-off leg. In the women's 400m freestyle, the world record is 3:55.38, set by Ariarne Titmus at the World Championships in Fukuoka in 2026. In the men's 200m butterfly, the world record is 1:50.34, set by Kristof Milak in 2026. In the women's 100m backstroke, Regan Smith set the world record at 57.13. Adam Peaty once dragged the men's 100m breaststroke below the 57-second mark in 2026.

Those are numbers anyone can look up. The harder part, and the part I consider more valuable, is the numbers nobody publishes.

During one two-hour session at a pool in Nha Trang, I counted eleven out of two hundred starts and turns in which young swimmers surfaced at or beyond the fifteen-metre mark. In another session with the same group, I counted the ratio of underwater swimming time to surface swimming time over 100m at roughly one to five, whereas the corresponding figure among world-class swimmers I measured from video was usually closer to one to three.

These numbers are not a large enough sample for scientific conclusions. But they are enough to raise a serious question about what the sessions actually contain.

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Takeaway: Swimming as a common language

I began this piece at a pool just before six in the morning, with a fourteen-year-old boy and a coach writing numbers in a notebook. I want to end somewhere else.

Every sport is its own universe, and I am lucky to be a traveller between those orbits. I learned to read a football match from those mornings counting dolphin kicks. I learned to read a swimming session from the basketball games I once followed through box scores. The language changes, but the question does not: who is doing the things nobody watches, and how much distance are those things creating?

If there is one proposal I want to carry into the next cycle, it is very specific and very small. I want one person standing at the fifteen-metre mark during every training session of youth squads. No modern measuring equipment required. Just a person, a notebook, and a stopwatch. Record the surfacing distance after every start and every turn. Do it for a year, across ten pools, with three hundred swimmers.

After a year, we would have a dataset no swimming nation in Southeast Asia possesses. And that dataset would answer a question medals cannot answer: where exactly are we slow, and by how much?

I do not know the answer. But I know where to put the camera. And I know that at some pool in Vietnam, at five forty tomorrow morning, a child will push off the wall, extend both arms, and begin a race nobody is scoring.

That race is worth counting.