NATIONAL MARITIME HISTORICAL SOCIETY

By Richard J. King

One day in 2002, a swimmer was making her way across Neko Bay in Antarctica when she was surrounded by chinstrap penguins. Taking a swim in Antarctica? Swimming with penguins? To explain how this came to pass, let’s start with the penguins.

The chinstrap penguin is one of the more common of the eighteen species of this group of flightless seabirds and one of a handful of species that raise their chicks on the shores of Antarctica. Each year, several million chinstrap penguins migrate to the Antarctic Peninsula and the islands in the region. So, seeing them here was not a surprise.

Lynne Cox swimming in Antarctic waters. Photo courtesy of Lynne Cox.

Seeing a person in the water was. It was the middle of December, and though it was the austral summer, the water was a frigid 32°F, nearing the freezing point of seawater in the region (typically about 28˚F). Lynne Cox was attempting to be the first known person to swim a mile in Antarctic waters wearing only a swim cap, goggles, and a regular bathing suit. When she slipped into the water from an anchored ship, she braced against the stinging cold and shock and found herself paddling far more rapidly than she wanted. She tried to relax and breathe more evenly.

Humans and other mammals, as well as birds, regulate their body temperature with blood flow. When a person immerses in cold water, the outer capillaries immediately shrink, forcing warm blood back to the regions of the body where it’s critical—the heart, brain, and internal organs. Physical activity, like shivering and swimming, can warm up the inner core as the extremities grow numb. Then blood vessels will reopen to send some blood to the rest of the body to avoid frostbite. The person might be doing okay in the cold water for a short while, but if activity can’t warm the blood sufficiently, hypothermia will set in. People die from being in frigid water, often quite quickly.

Penguins, though, who spend more than ¾ of their lives in the ocean, not only have a thick layer of insulating fat and densely set water-repellent feathers, but they have evolved a heat exchanging network of blood vessels in their wings and in their feet to warm incoming colder blood with the outgoing, freshly pumped warmer blood.

Lynne Cox, not quite a penguin, does have a rare physiological trait that makes her especially good at swimming in polar seas. Medical researchers discovered that her capillaries barely re-open in frigid water, meaning that cooled blood has less chance to recirculate into her head and torso. Cox explained in a 2019 interview: “My body basically says lose the hands, lose the feet, keep the core warm and keep the brain and lungs and heart going.” More importantly, Lynne Cox has a superhuman drive and mental strength for ocean swimming. When she was just 15 years old, she set the speed record for the swim across the English Channel. She repeated the feat and broke her own record a year later. She then became the first woman to swim across the Cook Strait in Aotearoa New Zealand. By the time of her Antarctic dip, Cox had also swum across the Straits of Magellan at the tip of South America, and in 1987 she swam across the 40°F international waters of the Bering Strait—a major public event symbolizing the thawing of the Cold War.

As she swam in the waters off Antarctica, adjusting her stroke to keep as much of her head out of the water as possible to stay warm, she maneuvered around brashes of ice—occasionally banging into ice chunks and pawing through water that was more slush than liquid. After 25 minutes and 1.2 miles, Cox started heading toward the shore. That’s when the penguins showed up.

“One hundred yards from shore, I saw chinstrap penguins sliding headfirst, like tiny black toboggans, down a steep snowbank,” Cox wrote. She explained how they used their tails like brakes in the snow and spread their wings out for balance. They dove into the water, then “porpoised” across the surface, leaping over the waves. Cox continued: “They zoomed under me in bursts of speed, and their bubbles exploded like white fireworks. More penguins joined in. One cannonballed off a ledge, another slipped on some ice and belly-flopped, and three penguins swam within inches of my hands. I reached out to touch one, but he swerved and flapped his wings, so he moved just beyond my fingertips. I had no idea why they were swimming with me, but I knew it was a good sign; it meant there were no killer whales or leopard seals in the area.”

Approaching the beach among the penguins, Lynne Cox had not only survived, but she had accomplished the first-ever Antarctic swim of its kind, pushing her body beyond anything anyone thought possible. It took her three months to get full feeling back in her fingers and toes.

We’re still waiting on the chinstrap penguins’ side of the story. I’m sure it’s b-r-r-r-illiant, but maybe they got cold feet?

Chinstrap penguins colony at Half Moon Island, Antarctica, across the Bransfield Strait from where Cox swam at Neko Bay.
Photo by Vadim Nefedov Alamy.com.