Moken sea nomads living on the Andaman Sea can see underwater like dolphins: Scientists discover how this Indigenous tribe trained their eyes to develop superhuman vision

Somewhere in the Andaman Sea, on a cluster of islands 50 kilometres off the coast of southern Thailand, children grow up doing something the human eye is not supposed to be able to do.

They dive into the sea without goggles, open their eyes underwater, and see clearly. Not vaguely. Not shapes and outlines. Clearly enough to pick out small brown clams resting against brown stones on the ocean floor.

These are the Moken, one of the last sea nomad peoples in the world. And what scientists found when they finally studied this ability in a formal setting was not what they expected.


Moken Tribe Underwater Vision Study

In the late 1990s, vision researcher Anna Gislen from Lund University in Sweden travelled to the Surin Islands in Thailand after a colleague, scientist Erika Schagatay, noticed something unusual while working with sea nomad communities in southern China. Moken children were picking out tiny shellfish from the seabed with a precision that should not have been visually possible.

Gislen spent nearly two decades working with the Moken to understand the ability. In 2003, she published a landmark study in the journal Current Biology that put a number to what she had seen. She compared 17 Moken children aged 7 to 13 with 18 European children of the same age, getting each group to dive underwater and read progressively finer line patterns on a card placed 50 centimetres away. Each pattern had to be correctly identified five times before it counted. One mistake meant failure.

The results, published in Current Biology and later cited extensively in Vision Research, were unambiguous. Moken children's underwater visual acuity measured 6.06 cycles per degree. European children measured 2.95. The Moken children were seeing more than twice as clearly underwater, according to the study.

How the Human Eye Sees Underwater

To understand why this is remarkable, it helps to understand what water does to human vision.

As Science magazine reported in its coverage of the research, human eyeballs are filled with a watery fluid that gives them nearly the same refractive index as water. This means light entering the eye underwater is not bent the same way as on land, and the unfocused light rays reduce visual clarity by roughly two thirds. It is why everything looks blurred when you open your eyes in a swimming pool.

What Moken children do to get around this is something most human eyes can do in theory but almost never do in practice.

Gislen's research, covered in detail by ScienceAlert and BBC Future, found that Moken children could constrict their pupils underwater to the smallest diameter humanly possible, around 2 millimetres, while European children's pupils did the opposite and opened slightly wider. A smaller pupil works like the opening in a pinhole camera, sharpening focus by limiting the angle of incoming light.

"Normally when you go underwater, everything is so blurry that the eye doesn't even try to accommodate, it's not a normal reflex," Gislen told the BBC. "But the Moken children are able to do both: they can make their pupils smaller and change their lens shape. Seals and dolphins have a similar adaptation."

Superhuman Vision or Trained Skill

The more consequential question the research raised was whether this was a genetic trait unique to the Moken, or something any child could learn.

According to a detailed analysis published by Seasia in January 2026, scientists believe the answer lies somewhere in between. The human eye has more flexibility than is typically used, and Moken children appear to train their visual system from a very young age through constant exposure to underwater tasks.

Gislen tested this directly. Within just one month, she managed to teach a group of European children to see underwater with the same clarity as Moken children, as ScienceAlert reported.

"The Moken do not do anything superhuman," she said, as quoted by Oddity Central. "They simply use the eye to its limits. I think it would be possible for all human beings to see better underwater, provided you are practiced."

However, as Medbound Times noted in its coverage of the research, this ability appears to exist only in children. Scientists believe the lens of the eye becomes less flexible with age, closing the window for this particular adaptation.

Moken People History and Culture

The Moken have lived across the Andaman Sea for centuries, moving between the roughly 800 islands that stretch along the coastlines of Myanmar and Thailand. Traditionally, as Seasia reported, they travel in wooden vessels called kabang, moving with the seasons and tides. Fishing, diving, and gathering shellfish form the backbone of their subsistence lifestyle, and from a very young age, Moken children are immersed in the marine environment.

Their name, in their own language, means "sea drowned." It is not a metaphor. It is a description of who they are.

The Moken came to worldwide attention in December 2004, when the Indian Ocean tsunami killed more than 200,000 people. As the Associated Press reported in December 2024, the few tourists on Moken-inhabited islands that day survived because locals, reading the receding tide, knew to move people to higher ground immediately. They had no seismographs or warning systems. They had centuries of oral knowledge about how the sea behaves before it kills.

That knowledge saved lives. And then the world moved on, and the Moken were left to deal with what came next.

Moken Tribe Threatened and Disappearing

The same isolation that preserved Moken culture for generations has become a source of legal vulnerability in the modern world.

Most Moken are stateless as a result of their nomadic lifestyle. They have no citizenship in Thailand or Myanmar. They cannot own property. They have no legal recourse when their rights are violated.

Human Rights Watch, in a detailed report on the Moken titled Stateless at Sea, documented serious rights violations by state authorities, particularly Myanmar's navy, including extortion, bribery, and confiscation of property. In Thailand, the report found, regulations including a ban on gathering sea products for trade and on chopping trees to build or repair their traditional kabang boats have steadily restricted the Moken's ability to live as they always have.

One Moken man described the shift plainly to Human Rights Watch. "Life was not comfortable, but we had freedom to go wherever we wanted to go. But then around 16 years ago, government officials told us we could not fish around Surin Islands anymore. They set so many rules and restrictions on our ways of life. My family now cannot earn enough from fishing. I come out on the beach, talking to tourists and begging money from them. It is embarrassing."

The sea itself has also changed. A Norwegian fisheries research vessel that surveyed the Myeik Archipelago in 1980 and again in 2013, as reported by the Phnom Penh Post, found that rampant overfishing had led to a 90 per cent fall in the biomass of open ocean fish species. Commercial fishing boats, many using dynamite and bottom trawlers, had swept through the waters the Moken had lived off for generations. The Moken population in Myanmar has fallen from around 5,000 to between 2,000 and 3,000 today, according to expert estimates cited in that same report.

Fishing restrictions, dwindling fish stocks, and the rise of tourism have pushed most Moken to settle on land, their movement now limited within national park boundaries, as Mongabay reported in February 2025. Some younger Moken have formed groups like the Moken Ocean Guardians, collecting plastic waste from the sea and selling it to recycling facilities in Bangkok, a way of staying connected to the ocean while earning enough to survive.

Al Jazeera's 101 East documentary on the Moken reported that outside the Surin Islands community, there are few Moken left who can recite their traditional tales. About 900 more traditional Moken remain in Thailand, while 4,000 land Moken exist as a separate group whose culture is disappearing even faster than their seafaring kin.

Moken Children Vision Future

There is a particular irony in the timing of global interest in the Moken's underwater vision. As Medbound Times noted, as the Moken lifestyle evolves and younger generations spend less time in the sea, researchers themselves question whether this extraordinary visual ability will persist. The skill exists because Moken children grow up in the water. Take the water away, and the adaptation goes with it.

What the research does leave behind, as Seasia's analysis concluded, is the understanding that the Moken ability is not a biological mutation exclusive to their genetics. It is an exceptional use of human visual potential, shaped by culture, environment, and early practice.

The Moken did not evolve a superpower. They simply used what they had, fully, from childhood, because their lives depended on it.

The question now is whether the culture that built that ability will still exist by the time science fully understands it.


(Disclaimer: The article is based on the publicly available information on Moken sea nomads.)