Have swimsuit, will travel. That's my mantra, finding windows of time and places to swim, no matter where I am, my semi-secret mission when I'm on the road.
It starts when I'm packing and I fall for swimming's minimalism all over again. Togs, goggles and I'm good to go. What other sporting equipment can be scrunched into a shoe in your suitcase?
Of course you need a pool, but I use the term loosely. Which brings me to the real reason I swim. It's not just that swimming is good, portable exercise and the best way I know to unfold one's limbs after a long-haul flight. It's this: nothing wakes you up to your surroundings and commits you to really being where you are like full-body contact with water.
Swim and you are literally, immediately, immersed in the landscape, particularly in natural places.
I've swum in mountain tarns surrounded by 3000-metre peaks and the grey-white tongues of glaciers in New Zealand. With so many tropical fish in Palawan, in the Philippines, it was like swimming in a free-range aquarium. I'll never forget my first dip in Tanzania after crossing sub-Saharan Africa on an overland truck: as soon as we rattled to a stop at the first beach we'd seen in two months, I sprinted into the sea's embrace like a long-missed lover.
I'll swim in a wetsuit if I must – and I have, in water clean enough to drink, while rafting Tasmania's pristine Franklin River. I've even had a dip in a drysuit, while sea kayaking in the Canadian Arctic, which was an odd, out-of-body experience: I felt the chill of the water through the fabric, without actually getting wet.
There were no wetsuits or drysuits on offer when I did my polar plunge in Antarctica, which was half the point. The other half was experiencing how leaping into the Southern Ocean wearing nothing but a bikini – and a harness attached to a safety rope to haul me back to the surface if I suffered a cardiac arrest – turns the simple act of submersion into an adventure, albeit a brief one.
It was over so quickly I remember almost nothing about it, except that it was snowing and there were car-sized chunks of ice floating nearby. I don't even remember the numbing cold, just the clumsy climb up the step-ladder to the deck afterwards and wrapping my hands around a hot lemon drink while someone wrapped me in a bathrobe and pointed me in the direction of the ship's sauna. If I hadn't been half-naked and dripping-wet, I might have daydreamed the whole thing.
We are designed to swim, I believe, despite the fact that we don't need to, to survive. We might not have gills, webbed digits or streamlined bodies, but we do have a few aquatic adaptations. Most of us can float, to some extent, because our bodies are less dense than water. And human babies up to the age of six months have a diving reflex also found in aquatic mammals such as otters, dolphins and seals: when underwater, infants automatically hold their breaths, slow their fast-beating hearts and reduce blood circulation to their tiny fingers and toes.
In 1942, a German pathologist, Max Westenhofer, dived deeper into this idea by proposing that we were once semi-aquatic and only recently returned to land. His Aquatic Ape Hypothesis sank like a stone. Incidentally, apes are generally afraid of the water and don't swim in the wild. So why do we?
Maybe because whatever our evolutionary story and wherever we find ourselves, it just feels good, on so many levels.
Wading into the blue and out of our depth, we can finally defy gravity – which feels all the more wonderful at the end of a Top End day of tough bushwalking. Shrug off that backpack, kick off those boots, wade into a croc-free swimming hole and you're suddenly as weightless as a rainbow serpent.
Ocean swims and swimming holidays are having their moment in the sun right now – there are canyon-swims in Arizona, coastal swims in Turkey, lake-bagging trips in the UK, escape-from-Alcatraz swims off San Francisco – and I can understand why. An ocean-swimming week at Lord Howe Island recently reminded me of swimming's twin blessings: shared experience and solitude.
"Swimming is between me and the water, nothing else," said the late American writer John Jerome in his 1997 book Blue Rooms: Ripples, Rivers, Pools, and Other Waters. "The moment the water encloses me, I am, gratefully, alone."
Swimming also lets us escape the sound-addled world, if only for as long as we can hold our breath. It's like putting on nature's noise-cancelling headphones and slipping away from the everyday into another space, if only temporarily.
Give me a free half-hour before dinner and I'll be doing laps in the hotel pool before you can say, "What time shall we meet in the lobby?"
Of course not all hotel pools are created equal. The most luxurious I've swum in was in the grounds of the Umaid Bhawan Palace, a Taj hotel in Rajasthan, where my turbaned butler padded up and down poolside, waiting to hand me a towel and a chilled bottle of water from a silver tray if ever I stopped swimming.
I once went on a wild tuk-tuk chase in search of a pool rumoured to be the best in northern Thailand, at a resort intriguingly called The Real Centre of the Universe. My aged, safari-suited driver did his best, but we never did find it. On a subsequent trip to northern Thailand, however, I stumbled upon hotel-pool heaven at the sprawling Imperial Chiang Mai Resort & Sports Club; the rooms were nothing special, but its pool was five-star, a sparkling Olympic-sized beauty I had all to myself.
Olympic pools, by the way, are a fairly recent innovation. At the first Olympics in 1896, the world's best swimmers competed in the sea off the coast of Athens, cheered on by 20,000 spectators lining the foreshore; four years later, in Paris, they raced down the Seine. Even when the first Olympic pool was built, bang in the middle of the track and field arena at London's first Olympics in 1908, it was a whopping 100 metres long. The 50-metre variety became de rigueur only after the second Paris Olympics in 1924.
For most of human history, we have swum "in the wild". There are 10,000-year-old rock paintings in Egypt depicting people swimming, possibly in the Nile. In the Middle Ages, swimming in Europe was thought to spread infections and cause epidemics, but by the 18th century public opinion had done a tumble-turn and we started swimming for good health, usually naked; wearing swimsuits was thought to dilute the beneficial effects.
Sea-bathing took off in the 1730s when English coastal towns such as Scarborough and Whitby became "swimming resorts" because of natural springs flowing from their sea cliffs. Men and boys would swim au naturel; women and girls had to wear loose neck-to-knee garments they'd change into inside "bathing machines", little wooden carts that could be rolled into the water so no one would see the ladies in their bathing suits.
It's hard to believe that in Australia, a nation of swimmers, daylight bathing became legal only in 1902, when a newspaper editor swam into the headlines by defying a public ban at Sydney's Manly Beach.
We wouldn't go to so much trouble, surely, if swimming didn't make us happy. Californian marine biologist, cognitive researcher and author Wallace J Nichols says that we each have a "blue mind" (the title of his new book), programmed to enjoy and benefit from proximity and contact with water. "We are beginning to learn that our brains are hardwired to react positively to water," writes Celine Cousteau, granddaughter of Jacques, in the book's foreword, "and that being near it can calm and connect us, increase innovation and insight, and even heal what's broken."
If swimming were a drug, its purest form would be swimming with marine animals that show us how it's done.
Swimming with Galapagos sea lions that sped like living torpedoes past me, with sea turtles that seemed to fly through the water, with 300 dusky dolphins off coast of Kaikoura in New Zealand's South Island and, most memorably, with 16 curious minke whales that circled my companions and me for an entire day while we clung to a line behind our live-aboard boat at the northern end of the Great Barrier Reef – these have been the underwater pinnacles of my travelling life.
If you really want to swim like a marine mammal, of course, you've got to lose the swimsuit. Less is more, when it comes to mingling with the elements. Find an empty beach, dash into the surf and let the waves tingle you all over – without having to worry about losing your top or getting sand in your pants. Failing that, there's always the secret skinny-dip. Last summer a girlfriend and I had a glorious, impromptu swim in Lake Geneva, in our undies, while tourists peered down from the parapets of a nearby 12th-century chateau, oblivious to our near-nudity.
I've learned a few things from swimming around the world. It's impossible not to get lost in the change-room underworld of a Budapest thermal bath complex, for instance. The direction people swim laps usually matches the direction of traffic in that country; keep left in Commonwealth countries to avoid mid-lane collisions, swim anticlockwise in Europe. And almost everyone does it: whether we're in the Solomon Islands or Siberia, we want to swim, perhaps need to.
I know I do. Having fed this obsession for some years now, it shows no sign of abating. My swimsuits wear out, my goggles fog up; I replace them and swim on. Bath-warm or brass-monkeys, stormy or still, crowded or calm, there's nothing like communing with water, anywhere and in any way you can, to bring you back to your senses and remind you that the world really is your swimming pool.