Beneath the Surface: Where Vietnamese Swimming Still Owes Asia a Few Percentages

In lane four, a Vietnamese swimmer touches the wall, rolls over, and surfaces just as the electronic clock ticks into the seventh second. In the next lane, the rival is still underwater, body undulating in a dolphin rhythm, and only breaks the surface after opening a gap of nearly a body length. The stands see nothing but two calm strips of water. But the race, in reality, was already decided in that underwater instant, before anyone threw a single stroke. Numbers only retell; tactics begin with mistakes. And the mistake here is not a botched stroke, but a stroke left blank.

In swimming, there is a rule few spectators notice: after the start and after every turn, a competitor may stay underwater for a maximum of 15 meters. In butterfly, backstroke, and freestyle, that underwater stretch is almost a fifth stroke, an acceleration that uses no arms, only the body's wave. At world level, most of the speed in a short lap is generated in the first 15 meters after the turn, not in the arm-stroking stretch in the middle of the pool. In other words, the race splits into two halves: the surfaced part, which everyone sees, and the submerged part, which almost no one measures.

Vietnamese swimming has come a long way. From the run of SEA Games medals by Nguyen Thi Anh Vien to Nguyen Huy Hoang's silver in the 1,500-meter freestyle at the 2026 Asian Games in Jakarta, we have shown we can stand on the podium at continental level. The 31st SEA Games, hosted in Hanoi in 2026, saw the host swimmers take a string of golds, and that created a very clear sense of progress.

But between a SEA Games medal and an Olympic final berth, the gap is not in arm strength. It lies in the things the eye cannot see. Southeast Asia has very strong rivals such as Singapore, and at continental level, Japan and China are the two leading swimming nations. Against them, Vietnamese swimmers lose neither in ambition nor in basic physical foundation. They lose in the details that get overlooked.

I have spent years watching indoor and outdoor meets, recording every wall touch by Vietnamese swimmers and comparing them with Asian rivals. What draws my attention is not their stroke rate, but the time they spend under the surface. Over the same distance, with the same tactics, Vietnamese swimmers tend to surface one to two meters earlier than their rivals after each turn. One meter sounds small. But in a 1,500-meter race with thirty turns, it compounds into a gap that no effort in the surfaced stretch can close.

Let us split a lap into phases to see it clearly. Phase one is the start and dive. Phase two is the surfaced stretch. Phase three is the approach to the wall and the turn. Phase four is the underwater glide after the turn. In phase two, Vietnamese swimmers are not at all inferior. On some short distances, our stroke rate even matches Asia's leading group. The problem lies in phase one and phase four, the phases when spectators usually turn away for a drink.

Movement science calls the dolphin kick after the start and after the turn the fifth wave. While a swimmer is still underwater, they do not face surface-wave drag, and their body can generate more propulsion than when stroking. That is why world records in short freestyle events keep falling to swimmers who hold a long, powerful underwater phase. But holding that phase is not only a technical matter. It is a physiological problem: the abdominal muscles, lower back, and thighs must endure an enormous load of lactic acid while the lungs are compressed. A good underwater phase demands core strength, controlled breath-holding, and above all the courage not to surface too early.

There is one technical detail I always check when reviewing turn footage: the position of the feet as they hit the wall. A good push-off begins with the soles pressed flat, both legs bent at the right angle, and the body stretching into an arrow line the instant it leaves the wall. If the shoulders rise by even a few degrees, drag increases immediately. Among Vietnamese swimmers, I often see a small flaw: they rotate quickly but lose part of the push because the body has not fully extended. That flaw does not show on the clock over 50 meters, but over 400 meters it is an entire results sheet.

Here, I recall sitting beside a veteran swimming coach in Hanoi. He said something that stayed with me for months: "We teach children to stroke from the age of six, but we only start teaching them to swim underwater at fourteen." That sentence sums up the whole problem. The technical foundation of Vietnamese swimming is built on the surfaced part of the water, while the international arena is decided in the submerged part.

A swimmer's movement map is like a chess game: read the intent, guess the next move. When I trace a Vietnamese swimmer's path through thirty turns, I see a repeating pattern: they surface at the fifth or sixth meter, while continental rivals surface at the eleventh or twelfth. Six meters of difference, multiplied by thirty turns, is nearly two hundred meters swum at a drag disadvantage. No effort in the surfaced stretch can make up for that number.

This does not mean Vietnamese swimmers are weak. On the contrary, reaching their current results while leaving nearly a fifth of the distance blank is an encouraging signal. It means that if that blank is filled, the room for improvement is still very large. In the 200-meter individual medley or the 400-meter individual medley, where each turn changes the stroke, the underwater phase after the turn matters even more, because it is the bridge between two completely different strokes. A good medley swimmer is someone who turns every wall touch into a fresh start.

I once sat analyzing data from a national youth meet and noticed a paradox: the swimmers with the best 50-meter results were usually those who held the shortest underwater phase. They won on pure power. But when they moved up to 200 and 400 meters, it was precisely those who held the underwater phase longer who pulled ahead. This is the point many youth training programs in Vietnam miss: they optimize for short distances, then are surprised when swimmers do not progress over long distances.

Injury risk also deserves mention. The repeated dolphin kick puts great stress on the lower back and hip joints. In breaststroke, the knee is the hotspot. In butterfly and freestyle, the shoulder is the most vulnerable spot, to the point that the profession has a dedicated term for it. A training program that wants to increase underwater time must be matched by a corresponding injury-prevention program; otherwise, we trade short-term results for the swimmer's long-term career.

The counter-intuitive angle lies here: when we talk about the gap between Vietnamese swimming and the continent, we usually blame physique, nutrition, and facilities. Those are real factors, but they are not the biggest blind spot. The biggest blind spot is how we measure progress. We measure by the final result, by the medal, by the national record. We rarely measure by underwater time, by the meters glided after each turn, by the speed of surfacing.

My 2026 mistake reminded me that data is a mirror, not a lamp. It reflects what we choose to look at, and ignores what we do not measure. If a swimming nation only measures the surfaced part, it will keep optimizing for the surfaced part. And the surfaced part, however beautiful, is only half the race.

I do not believe in hunches. I believe in how many variables that hunch has been loaded with. And the most important variable for Vietnamese swimming, so far, has not been loaded enough: the submerged part. A swimming nation can win the SEA Games with the surfaced part, but it cannot reach an Olympic final if it leaves the submerged part blank.

The question left behind is not how to swim faster, but how to measure what we are forgetting. When a swimming nation starts counting the meters glided after each turn, it will start to see its true gap. And only when it sees it can it close it.