Scientists have identified unique genetic variants in South Korean sea women that may explain how they withstand hours of frigid, breath-hold diving.
The haenyeo of Jeju Island, some of whom continue diving into their 80s, carry DNA changes found in no other studied population that researchers believe help protect them and even their unborn children during extreme underwater exertion. Melissa Ilardo, PhD, a University of Utah Health assistant professor of biomedical informatics and senior author on the study, spent time observing the women at work.
“I saw women over 80 diving off a boat before it even stopped moving,” Ilardo said.
The research, conducted by teams at the University of Utah and UCLA, revealed that haenyeo divers are more than four times more likely than mainland Koreans to carry a genetic variant linked to lower blood pressure during dives. Many of the women continue working through pregnancy, and the trait may offer protective benefits to both mother and fetus under sustained physical stress.
A second genetic difference relates to cold-based pain tolerance, though researchers have not yet confirmed whether it directly boosts the ability to endure freezing temperatures. Sea temperatures around Jeju drop close to freezing in winter, yet the women rarely stop working because of it.
“I asked them once if they would stop diving if it got cold enough,” Ilardo explained. “They said that as long as the wind alarm doesn’t go off, they’ll still get in the water.”
The haenyeo typically begin work at 6am, descending up to 60 feet without oxygen tanks to harvest seaweed, abalone and shellfish from the seafloor. A single session can include roughly 100 dives totaling up to seven hours underwater. While the genetic variants are shared across Jeju Island’s broader population, the dramatic physiological adaptations come from decades of practice. An untrained person from Jeju experiences a heart rate drop of about 20 beats per minute during a simulated dive; lifelong haenyeo can see that reduction double.
“They’re absolutely extraordinary women,” Ilardo said.
The tradition, recognized by UNESCO as an Intangible Cultural Heritage, faces collapse from multiple pressures. No insurance covers the work because it is considered too dangerous. Global warming has reduced sea life in shallow waters, forcing the women to work harder without adopting the deep-diving air tanks they have always refused. A training school established in the early 2000s has seen only about 5% of attendees actually become haenyeo.
Filmmaker Sue Kim, who first encountered the divers as a child visiting South Korea, documented their struggle in “The Last of the Sea Women,” produced alongside Nobel Peace Prize winner Malala Yousafzai. Gaining access took considerable time.
“They wanted to talk about the fact that they felt that they were on the verge of extinction,” Kim said.
The women have also become political advocates. Haenyeo Soon Deok Jang traveled to the UN Human Rights Council in Geneva to protest Japan’s release of treated radioactive water from the Fukushima plant into waters bordering Jeju.
A small counter-trend offers modest hope. Younger women from other islands have begun building social media followings around the job’s flexible, family-friendly hours. The veteran haenyeo now call them “their babies,” and the newcomers reciprocate with the honorific “aunties.”
Researchers hope the genetic findings may eventually contribute to stroke treatment, given Jeju Island’s notably low stroke mortality rate among Korean regions.
“The Last of the Sea Women” continues screening at festivals internationally.
