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The Wonder of Cold Water Swimming

Rain pummels the sea around my bobbing head. The rest of my body, suspended beneath the swell, clenches in the cold ocean. I take in gasps of salty air and exhale clouds of condensation that rise and disappear into the dark winter sky. It’s a frigid day to be snorkelling on the jagged rocky coast...

Rain pummels the sea around my bobbing head.

The rest of my body, suspended beneath the swell, clenches in the cold ocean.

I take in gasps of salty air and exhale clouds of condensation that rise and disappear into the dark winter sky. It’s a frigid day to be snorkelling on the jagged rocky coast off Cape Point wearing nothing but shorts and a dive mask, but I remind myself not to worry.

The amazing thing about my body is that it will soon adapt to the cold water.

Already, the terrible razors I felt on my fingers and toes when first wading into the sea are gone. My skin is slowly taking on the temperature of the surrounding ocean, and I can feel my chest burning warm in the cool blue.

“Deep, short breaths of air!” shouts Craig through the wind and rain.

Image by Craig Foster

Craig Foster is an amphibian.

He spends more time in the kelp forests around Cape Town than most fur seals.

Every day of his life, rain or shine—and today, the weather could not be worse—he enters the chill waters near his house on the Cape Peninsula to study and record the marine creatures along it’s shore.

An award-winning anthropology and nature filmmaker, Craig believes that being cold was a regular part of the lives of our early stone age ancestors, and over time, we have evolved mental and physiological adaptations to these extreme environments. A wetsuit, he says, disrupts the body’s natural coping mechanisms in the water.

As a freediver I’m accustomed to covering myself in sticky neoprene before slipping into the ocean. But today, on the icy winter solstice, Craig has invited me to push my body to it’s limits; to immerse myself in the ocean environment sans wetsuit—to experience what he calls the ‘primal joy’ of skin diving.

Most mammals, including ourselves, are surprisingly well adapted to the cold.

One of these adaptations is our very own built in thermal ‘wetsuit’ called brown fat—an invisible tissue that creates heat energy when activated by the cold.

Once thought to only occur in newborn babies, recent studies have shown that brown fat in adults is so effective at burning calories that cold water swimming is now being punted as a brilliant way to lose weight and prevent obesity. Swimming also triggers our mammalian dive reflex—or Master Switch of Life—an ancient adaptation to cold water that slows the heart, raises our core temperature and shunts blood from our arms and legs to vital organs to keep them warm and oxygenated in extreme conditions.

Fending off the cold is also a mental game. Buddhists monks in the Himalayas have been known to dramatically raise their own body temperature during meditation. In one Harvard study, wet towels were placed over the meditating monks to see if it could lower their core temperature. As they meditated, steam rose off their bodies and after a few hours, the towels were dry.

The famous polar ice swimmer, Lewis Pugh, was also amazingly able to raise his core temperature 2 degrees before entering the freezing arctic water. All he had to do was anticipate being cold, and his body simply knew what to do.

“How are you doing?” asks Craig.

The weather has taken a turn for the worse. A cold wind sweeps across the grey bay, whipping spray off the tips of waves.

My body tingles, and my heart beats slowly. “I’m warm.”

Photo by Craig Foster

I sink my head beneath the frothing water where it’s quiet.

The long bronze kelp trunks sway to and fro in the surge, and sediment swirls around like a silent cyclone. I draw a deep breath of air through my snorkel, and grab hold of a branch that disappears down into the murky blue. I begin to climb. Down, down and down I climb. This is the purest moment of a dive, the feeling of freefalling into the blue abyss. The deeper I go, the quieter it gets, until I hang like an astronaut on the ocean floor.

A gap of light brightens the water and all the colours come to life. Spiny red and yellow urchins carpet the floor; giant orange sponges hang off the rock walls, silver fish glint, white jellies drift, and shades of anemone and mollusk cling to the rocks. I’m just 100 meters from the main coastal road that winds on to the sprawling city of Cape Town. Yet down here, in this cold swaying forest, I may as well be exploring a distant ocean wilderness.

Craig weaves through the kelp branches nearby, searching between the gaps in the rocks for an octopus den he knows well. The octopus is one of his favourite subjects. After years of skin diving near his home, he has developed kinships with specific individuals who recognise and trust him, and filmed their unique behaviour. He’s seen these intelligent animals utilise basic tools, stalk and hunt lobsters on the ocean floor, and watched them ‘net’ the crustaceans with their entire bodies.

For Craig, the kelp forests are an unexplored realm, and science has only scraped the surface of what’s down here in the cold nutrient-rich coastal waters around Cape Town—right under the noses of over four million people.

Photo by Craig Foster

One kick and I burst above the surface, thick drops of rain thumping my cheeks.

The weather has taken a turn for the worse, yet Craig is beaming as if he is enjoying a fine snorkel in the Bahamas.

“I’m impressed by your cold resistance,” he says when I give the OK signal. Hypothermia is defined as a drop in core body temperature below 35°C. The average person, it is believed, can happily survive for between one and two hours in this temperature water (12°C) before the onset of hypothermia.

After an hour of exposure, symptoms include uncontrolled shivering, exhaustion, unconsciousness and finally, given a few more hours, death. But like most forms of ‘exercise’, it is possible to condition one’s body to survive for longer. After years of diving, Craig has built up stores of brown fat, providing a longer supply of metabolic energy when diving.

Regular exposure has also dramatically enhanced his body’s ability to thermoregulate—maintain a stable core internal temperature—and conserve heat. Aside from longer survival times, studies have shown that there are incredible health benefits of regular cold exposure, including a stronger immunity against cancer, enhanced pain tolerance, warding off depression, and greater stress resistance.

There are also anecdotal reports of people who simply feel happier, more focussed and energised with regular exposure to the cold. Perhaps this is the what Craig means when he talks about the ‘primal joy’ of skin diving—that innate sense of freedom and exhilaration that comes from truly exposing oneself to the elements.

We flop out of the tide and stumble onto the rocks, drunk from gravity.

The air feels strangely warm, and I stand still for a while in the wind, invincible against the worsening weather. “We were in the water for 50 minutes!” says Craig while doing pushups on the rocks.

Ironically, the most dangerous part of cold water swimming occurs just after leaving the water. As the body starts to normalise, it experiences what is known as an ‘afterdrop’. This happens when warm blood in the chest is redistributed to the arms and legs, cooling the blood further. Exercise—and involuntary shivering—compensates for this, preventing a further drop in core body temperature.

We both dress in warm clothes, do a couple pushups, and then sit for a while on the rocks, teeth chattering.

“Is it worth the cold?” Craig asks.

The sun peeks below the storm clouds like a log fire in the snow, thawing my cheeks.

“I think so,” I reply. I’m warmer now.

But I can already feel the pull of the deep cold blue.

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Meet the Author

Author Photo Paul Steyn
Paul Steyn is a widely-published multi-media content producer from South Africa, and regular contributor to National Geographic News and blogs. Having guided throughout Africa for some years, he went on to edit a prominent travel and wildlife magazine, and now focuses on nature storytelling in all its forms. In 2013, he joined a team of researchers and Bayei on a 250km transect of the Okavango Delta on traditional mokoros. In 2016, he accompanied the Great Elephant Census team in Tanzania and broke the groundbreaking results on National Geographic News . Contact: Follow Paul on Twitter or Instagram