Lynne Cox: The Ice Maiden

Lynne Cox likes nothing more than a freezing-cold challenge. Over the past 30 years, the endurance swimmer has crossed the English Channel, swam from Alaska to Siberia and taken a dip off Antarctica. Now, as her extraordinary first book is published, she faces the ultimate test: persuading our writer Andrew Gumbel to get his trunks on

It is a sun-kissed southern California afternoon in April - perhaps not the toastiest month of year to go for a swim with Lynne Cox, but not exactly the cruellest either. For her, of course, the assignment is a doddle. The beaches of northern Orange County, between the surfing waves of Huntington Beach and the hulking cranes of Long Beach harbour, may be where she trains on a regular basis. But her true medium, the peculiarly exquisite form of watery hell she has made her very own, is several drastic ticks of the thermometer colder than anything she or I could ever encounter here.

It is a sun-kissed southern California afternoon in April - perhaps not the toastiest month of year to go for a swim with Lynne Cox, but not exactly the cruellest either. For her, of course, the assignment is a doddle. The beaches of northern Orange County, between the surfing waves of Huntington Beach and the hulking cranes of Long Beach harbour, may be where she trains on a regular basis. But her true medium, the peculiarly exquisite form of watery hell she has made her very own, is several drastic ticks of the thermometer colder than anything she or I could ever encounter here.

Cox, after all, is famous for swimming in the kind of temperatures that would send the average human being into immediate cardiac arrest. She crossed the notoriously intemperate Strait of Magellan, on the tip of South America, before she was 20. She negotiated the treacherous currents of Cold War geopolitics as well as near-freezing temperatures to swim the Bering Strait between Alaska and Siberia in the mid-1980s. Three years ago, she capped even these achievements by doing what no human being ought to be capable of doing in a swimsuit: she swam just over a mile in the glacial ice soup of Antarctica - an experience she describes as a "great dream".

As I gun down the final stretch of the Pacific Coast Highway to our appointment, I wonder just how much gentle humouring I'm letting myself in for. As it turns out, I have nothing to worry about. Cox is not remotely the fiercely competitive sort of athlete who will shoot me dead with a single withering glance. She is friendly, open and devoid of pretence. For a while at least, I think this is going to be fun.

"Slide your feet along the sand to avoid the stingrays," she warns with motherly concern. "If you get stung your foot will blow up to the size of a football. The sand you kick up by sliding your feet will keep them away."

As we arrive at Surfside Beach, though, Mother Nature turns downright capricious. The stiff ocean breeze turns into a 40mph howl. The sun vanishes behind a bank of cloud. The only people to be seen, in or out of the water, are a handful of hardcore kite surfers in wetsuits, and even they scramble out of the waves as the weather deteriorates. I'm on the beach in my trousers and a thick sweater, and I'm shivering.

"Lynne," I say, a little forlornly, "I think you're on your own."

She understands perfectly. All her life, she's had far stronger swimmers than I'll ever be baulking at her sheer endurance and leaving her to it. Without missing a beat, she slips out of her tracksuit, parts her long brown hair neatly in two at the back, folds each half into her green cap and wades into the raging surf. In addition to the wind, there's a nasty riptide pulling to one side. She swims against it for one or two minutes, not allowing herself to be pulled backwards but not making any forward progress either.

For her, I realise, this is the equivalent of hopping into a lap pool, exercise so gentle it is almost ridiculous. When she gets out after 25 minutes or so, she stands on the beach quite happily, unbothered by the plummeting air temperature and the rapid approach of nightfall. She doesn't even have a towel, letting the howling wind dry her skin as though it was midsummer. When she invites me to touch her bare arm, I realise she is considerably warmer than I am. In fact, she feels like a furnace.

As she explains in her thrilling new memoir Swimming to Antarctica, Cox has a very unusual body and a very unusual metabolism. Almost all people are either negatively buoyant, which is to say water tends to drag them down, or positively buoyant, which means their distribution of body fat tends to make them bob on the surface. Cox, though, enjoys exactly neutral buoyancy, which is to say her body density is the same as seawater. A research physiologist at the University of California in Santa Barbara once told her: "Your proportion of fat to muscle is perfectly balanced so you don't float or sink in the water; you're at one with the water. We've never seen anything like this before."

The other extraordinary thing about her is, of course, her ability to resist cold. Most people, when exposed to water colder than about 10C, lose body heat with extreme rapidity and go into hypothermic shock. Even relatively temperate ocean waters will do them in over a relatively short time. In Cox's case, though, her core body temperature is actually capable of increasing over the course of a long swim. That's not true in the harsher conditions of Alaska, or Siberia, or the south Atlantic, but even there her body has a remarkable ability to redirect its heat to the vital organs of her brain, chest and abdomen. After her limbs have gone blue and splotchy - like a corpse's, as she observed during her Bering Strait swim - her metabolism keeps going with remarkable strength, and with it her ability to keep pushing forward through the water.

Cold is, in many ways, her most comfortable medium. Since her book came out in the US last year, she has been spending a lot of time on the corporate lecture circuit and staying in hotels with heated pools. "They roast me alive!" she says, only half-jokingly. She doesn't have especially fond memories of another politically momentous swim, from Egypt to Israel and from Israel to Jordan, right around the time of the signing of the Israel-Jordan peace accord of 1994. "The water temperature was about 80F and the air was about 90F," she says with obvious distaste. Standing out here on the wind-blown shores of a distinctly tepid Pacific, it sounds pretty ideal to me. Then again, if I ever visited Siberia, I'd never think to pack a pair of swimming trunks.

As the book makes clear, Cox's life has been little short of extraordinary. She broke the record for crossing the English Channel when she was just 15, reaching what was, at the time, her life's ambition before she was even old enough to drive. She dodged predatory sharks in the Cook Strait between the North and South islands of New Zealand, faced more sharks as well as yellow-bellied sea snakes off the Cape of Good Hope, was bitten to pieces by mee fleas - a form of microscopic mosquito larva - in Lake Myvatn, Iceland, and used her bare arms to chop through pan ice in Glacier Bay, Alaska.

Sometimes the obstacles were as unexpected as they were unpleasant. In 1990 on another symbolic swim, along the Spree between East and West Berlin, she had to dodge mines and razor wire, not all of which had been cleared out of the river after the Wall fell and the city was reunified. Even on the surface, she had to contend with dead rats and condoms.

In Cairo in the early 1970s, a race down the Nile turned into the closest thing to disaster she has ever faced. Having developed dysentery during her practice swims, she became dangerously dehydrated and eventually had to pull out - not before negotiating sewage-strewn water, more dead rats and the rib cage of a dead dog that she accidentally punched her hand through.

The determination that Cox brings to her sport is not something that gets in the way of her relations with her fellow humans. On the contrary, her personality is every bit as buoyant as her body. Her impulse is not to aggrandise herself but to dig out what is extraordinary and fascinating in others, in much the same way that she has, during her toughest challenges, dug for the extraordinary within herself. "Your body is so amazing," she says with genuine wonder. "It wants to survive so bad."

The use of the second person is characteristically telling; Cox is not interested in promoting her own exceptional ability so much as the abilities of human beings in general. This trait not only makes her a gracious sportswoman, it has also served her very well as she has sought to use her endurance swims as a diplomatic tool to break down barriers between peoples and countries. It also makes her a hell of a writer - observant, supremely aware and endowed with a roaringly sharp sense of humour.

Swimming to Antarctica, in fact, tells two stories: the compellingly reconstructed thrill-ride of her swimming career and also, tucked in the folds of her fluid prose, her maturing as a storyteller. Cox has wanted to be a published author almost as long as she has been plunging into near-freezing sea water. Even as a teenager, she says, "I wanted to write even more than I wanted to be a swimmer."

The first draft of her memoir dates to her final year in college, at which point it was largely an account of exploits crossing the English Channel. She was rejected then, and continued to be rejected for the next 21 years, as the manuscript went through countless drafts and revisions. Her college writing teacher at UC Santa Barbara believed in her, though, and as time went on she accumulated ever more fans, some of them with genuine influence.

Charles Swanson, the author of a 1999 profile in the New Yorker, was a great source of encouragement, as was the novelist Anne Rice, to whom she is distantly related. The acknowledgements in her book constitute, in fact, quite some list of notables, including the Hollywood cinematographer Allen Daviau (a cousin of hers), and Arthur Sulzberger Jr, the publisher of the New York Times, who read and championed her manuscript after meeting her at a lecture.

Her facility with other people, both the distinguished and the ordinary, accounts for a large part of the direction that her swimming exploits took. When she crossed the Cook Strait in 1974, the people of New Zealand cheered her on as a storm blew up, the waves rose to eight feet, and she felt "as if I were swimming through a washing machine on spin cycle". Boats in the area signalled to her, an Air New Zealand jet dipped its wing and, once she arrived safely on shore, church bells rang out from one end of the country to the other.

That experience made her realise, as she writes, that a swim can be "a way to bridge the distance between peoples and nations". Within a couple of years, she set her heart on breaking down the barriers of the Cold War and crossing the Bering Strait. The effort turned into an 11-year marathon of letter-writing and lobbying. At first, nobody believed the crossing was a physical possibility. Then they dismissed it out of hand for geopolitical reasons - the US-Russian border had been closed since the Second World War and the Siberian side was also home to one of the most sensitive Soviet military bases anywhere.

Cox never gave up, though, and through Armand Hammer, the oil billionaire and philanthropist, she obtained an introduction to the Soviet cultural attaché in San Francisco. Via the staff of Ted Turner's Goodwill Games, which took place in Moscow in 1986, she pressured Mikhail Gorbachev into viewing her swim as an expression of glasnost.

In the summer of 1987, she and her crew travelled to Alaska not knowing if they would obtain permission or not. The Soviets became convinced she would attempt the swim anyway and eventually consented for the sake of international good form.

A delegation of 50 notables was waiting on the Soviet side of the border as Cox made the swim. When she landed, the scrutiny from the Soviet media was so intense that Cox, still in her wet swimsuit and nothing else, almost succumbed to hypothermia. Among the few things she had requested for her landing was a babushka, by which she meant a brightly coloured shawl. But the Soviets interpreted the word in its Russian meaning of grandmother.

As she was warming up, one of the doctors monitoring her progress started showing her photographs. Cox asked if these were the doctor's children. "Nyet," she responded. "Not children. I babushka... Grandchildren."

The moment was big in the West, but it was little short of huge in the Soviet Union. "I'm still recognised in Moscow," she says. When Cox returned to Siberia to swim Lake Baikal a few years later, she was told one of the capes on the lake would be named after her if she completed the crossing. "OK, that's motivation," she remembers thinking. Sure enough, there is now a Cape Lynne Cox - just a few hundred yards down from Cape Leo Tolstoy.

Cox's good fortune is to excel at a sport in which age is not an obstacle. Now 47, she is still casting about for new adventures - even if the lecture circuit has taken some of the edge off her physical form recently. Over and above the satisfaction of being published, she has solved one big problem with her book, and that is the riddle of how to make a reasonable living. For most of her life she has depended either on her parents - her admirably supportive "heroes" with whom she still lives - or on dribs and drabs of corporate sponsorship.

This year, for the first time, she has made something resembling a decent salary. On the downside, however, she has also had to face the unpleasant reality of significant taxation. "They have taken so much of my income I'm broke all over again!" she exclaims. Next to the bureaucratic exigencies of America's Internal Revenue Service, a plunge in ice-cold water in some far-flung corner of the earth doesn't seem quite so daunting after all.

'Swimming to Antarctica: Tales of a Long-Distance Swimmer' is published on 19 May by Weidenfeld & Nicolson, priced £18.99. To order your copy for the special price of £16.99, including p&p, call Independent Books on 08700 798897