The human body can adapt to remarkable environments, but few examples are as impressive as the Haenyeo of South Korea.
These women have spent generations diving deep into the sea without breathing equipment to collect seafood.
Their extraordinary lifestyle has attracted scientists who want to understand how the body adapts to years of extreme physical activity.
The Haenyeo live on Jeju Island, about 80 kilometres south of mainland South Korea. Many continue diving well into their 60s, 70s, and even 80s.
They regularly dive to depths of around 20 metres and spend hours in cold seawater, relying only on their breath-holding ability and years of experience.
A research team led by scientists from the University of Utah studied the Haenyeo to learn whether their bodies had developed unique biological features. The researchers measured heart rate and blood pressure and analysed DNA samples to look for genetic differences that might explain their remarkable abilities.
The study found two important genetic variations that appear to be more common in people from Jeju Island. One variation is linked to blood pressure. Normally, holding your breath underwater causes blood pressure to rise, which can place extra stress on the heart and blood vessels.
The researchers discovered that the Haenyeo were much more likely to carry a genetic change that may help keep blood pressure lower while diving. This could reduce the strain placed on the body during repeated breath-hold dives. The finding may also help explain historical reports that some Haenyeo continued diving safely during pregnancy, although such activity would not be recommended today.
The second genetic variation appears to affect how the body senses cold. The waters around Jeju Island become very cold during winter, yet the Haenyeo continue diving throughout the year unless weather conditions become dangerous. The researchers believe this genetic difference may help reduce sensitivity to cold discomfort, although this idea still needs further study.
Genes are only one part of the story. Years of daily diving also strengthen the body’s natural diving reflex, which slows the heart rate to conserve oxygen while underwater. Most people experience only a moderate slowing of the heartbeat, but experienced Haenyeo showed a much stronger response, demonstrating how lifelong training shapes the body.
Interestingly, these genetic traits are found in many people living on Jeju Island, not only in professional divers. This suggests that both inherited biology and decades of practice combine to produce the Haenyeo’s exceptional abilities.
The findings may have important medical value beyond diving. High blood pressure remains one of the leading causes of heart disease and stroke worldwide. If scientists can understand exactly how this genetic variation helps regulate blood pressure, it may eventually inspire new medicines or treatments for hypertension.
The researchers also noted that Jeju Island has one of the lowest stroke death rates in South Korea. Although it is too early to conclude that the genetic variation is responsible, it provides another interesting question for future research.
This study offers valuable new insights into how the human body adapts to challenging environments. Its strengths include combining genetic testing with physical measurements in a unique population that has been shaped by centuries of diving.
However, the research does not prove that these genetic differences alone cause better health or lower blood pressure. Larger studies will be needed to understand exactly how these genes work and whether the discoveries can be translated into treatments for people around the world.
If you care about blood pressure, please read studies about how diets could help lower high blood pressure, and 3 grams of omega-3s a day keep high blood pressure at bay.
For more health information, please see recent studies about how tea and coffee influence your risk of high blood pressure, and results showing this olive oil could reduce blood pressure in healthy people.
Copyright © 2026 Knowridge Science Report. All rights reserved.
