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'Euphoric': Why is there a boom in sea swimming, and is it good for you?

During lockdown, chief AFL writer Jake Niall girded his loins and swam in the sea. He and his gang of “aquanauts” were not the only ones. What is the appeal of sea swimming? Is it medically beneficial? And what are the perils?

My first foray into lockdown swimming was in mid-May, about two months after pools shut. At the suggestion of a friend I journeyed to Williamstown Beach in suburban Melbourne to tentatively resume swimming.

Clad in a tattered wetsuit while wavering waist-deep near the Willy surf club ("why am I doing this?"), I finally dived in on that Sunday morning and surprisingly completed nearly a kilometre of freestyle and intermittent breaststroke between two poles about 100 metres from shore.

The cold attacked my extremities, turning hands and feet numb. But the body was otherwise fine. Or so I thought. "I feel OK," I told my fitter, hardier friend as I shivered on the shoreline.

"You are slurring your words,"⁣ he replied.

But within an hour my teeth stopped chattering and I felt slightly euphoric – the cold-water experience had triggered a rush.

I'd competed in some ocean swims along the coast over the years, but never seriously contemplated the notion of becoming a bay swimmer. Still, in Melbourne, where the winter sea water hovers around 10 degrees – bloody freezing, for those who've not tested it – Port Phillip Bay was open for business when pools were not at the height of the pandemic.

In Sydney, where the lockdown was much less severe but pools were still off limits for periods, locals also saw an uptick in swimmers congregating to dive into the waves – at least, until a pre-Christmas COVID cluster abruptly forced the closure of northern beaches (and pools).

While we don't have numbers that measure the growth in ocean and bay swimming during 2020, Jamie Lingham, the founder of Melbourne-based sea swimming community Shrinkäge (which they pronounce "Shrink-arj"), says his group quadrupled, from a hardy 15 to about 60.

"It's amazing to me how many people went to cold-water swimming through COVID," says Lingham, 48, who lives in the bayside suburb of Elwood and boasted an unbroken streak of 204 consecutive days of sea swimming – all without a wetsuit– when I joined him in the Elwood water in December.

Manly Beach is 700 or so kilometres from daggy Elwood – a world away in terms of water temperature (warmer), surf (real) and scenery, both above the waterline (it's prettier) and below (sea life is visible).

But members of Manly's famed ocean swimming community, Bold and Beautiful, also found COVID had increased demand for their daily morning ritual.

"People want to keep fit and they were working at home and they had more time [to swim]," says Julie Isbill, who founded the group in 2008 and has seen it grow from eight swimmers to thousands.

For those who discovered the thrill of cold water – the rush of adrenalin that follows a frigid swim in Melbourne winter or a joust with Sydney's surf – there may be no turning back to laps at the pool.

The man-made concrete cannot compete with nature – though Port Melbourne and Elwood beaches are hardly postcard material – which raises questions for me as I return, intermittently, to the comfort of 27-degree laps in chlorinated water and the less exhilarating experience of shuttling up and down in a crowded lane. Have pools become a dull, staid form of exercise, lacking the buzzand camaraderie of the ocean option? What exactly is the attraction of dipping in the sea? And what are its health benefits – and downsides?

What was the attraction of ocean swimming in lockdown?

Over time, as I enlisted others and our loose, regular ocean swimming group of five, six or seven swimmers took shape – dubbed the Aquanauts by our principal organiser, Sophie – I became inured to the dark, 10-degree waters of Port Melbourne, learning to wear two caps and upgrading to a 21st-century wetsuit.

Most of our group were travelling from the inner north, where the pools and pubs are plentiful, to the bay beaches – mainly Port Melbourne, Elwood or Williamstown.

By the end of July, as the second lockdown's five-kilometre rule scuppered our swimming, I'd managed about nine bay swims and the fitness results seemed superior to what one would gain from that modest quantity of swimming in the pool (more on that later).

But what really mattered was how you felt. Mentally, the bay offered a day release from COVID house arrest as well as adventure and esprit de corps.

How do different swim settings differ?

Our group's experience of the attractions of sea swimming is consistent with what Shrinkäge found as well as with the testimony of Sydney swimmers, including author and host of the ABC's The Drum Julia Baird, whose bestselling book Phosphorescence extols the virtues of daily ocean swimming in Manly, inspiring others to take to the sea. In Melbourne, a swimming group even named themselves Phosphorescence after Baird's book.

"It becomes like a ritual," says Baird, who has been swimming for more than a decade with Bold and Beautiful, sometimes deploying flippers "if the surf is huge".

"It's more than just exercise you do," she says. "It's something else you do to make yourself sane." In Melbourne, Lingham, whose migration business was hit hard by the pandemic, added extra frisson with commando-style 5.30am swims dubbed "black ops", since they took place in winter darkness. "You wear a [flashing] light on the back of your head so you don't get run over by a boat."

The spirit of adventure seems a drawcard for group members wherever they are, even if the nomenclature of Sydney and Melbourne's ocean swimming groups play to metropolitan stereotypes: Shrinkäge speaks to the colder climate and its humiliating effects and Aquanauts suggests exploration of an unhospitable environment while Bold and Beautiful are precisely what we would expect on the gorgeous north shore – named as they were, according to Isbill, by a Manly board rider, who one day asked: "What are you guys, The Bold and the Beautiful?"

(Meanwhile, during a stint on the Gold Coast where the AFL had relocated, I took to the ocean again: it was pleasant to dive into the 21-degree surf but by then my cold-water conditioning had muted the refreshment. It wasn't cold enough.)

How might swimming in the sea be better for your physical health?

In southern waters, what swimmers report about cold water's shock value is backed up by the University of Melbourne's Dr Kate Murphy, senior research fellow in the Centre for Muscle Research in the Department of Physiology and an ocean swimmer who's completed the 20-kilometre Rottnest Channel Swim in Western Australia.

The immersion in cold water triggers the swimmer to expend more energy than he or she would in more temperate water. "It [the body] expends energy to keep yourself warm," says Murphy. Thus, colder water swimming burns more calories.

Murphy says some of our white fat stores transform into "brown fat" when exposed to the cold. "The more exposure to cold water, the more brown fat you generate," she explains. The brown fat makes the body more efficient in maintaining warmth. "It means you can swim for longer without getting hypothermia... you're able to withstand the cold better."

This is why veterans of cold water, such as the famous Icebergers of Bondi and Brighton and the mainly wetsuit-averse Shrinkäge, develop an immunity to cold water, to the point that Lingham is planning to complete the Ice Mile – a mile of swimming in water that's 5 degrees or less, certified by the International Ice Swimming Association - near Cooma in the Snowy Mountains.

No wetsuit? "The whole point is you can't wear a wetsuit," he says.

Further north, according to Isbill, peak cold off Manly Beach is about 15 degrees – a bath, by Melbourne standards – while in summer it's closer to 20. Still, ploughing through choppy seas or surf should improve strength. "You need to pull your body over the waves," explains Murphy.

But if swimming in cold water might assist in shedding weight (relative to pool swimming), salt water – commonly viewed as an elixir – does not carry any special properties. Murphy says there are "not really" any physical benefits to salt water and the exception is "only in respect to body position" due to buoyancy, although "anecdotally, people say their skin feels better".

Does an ocean dip help with mental health?

From what I've observed and felt and heard from almost every ocean swimmer, the psychological benefits of cold water and ocean swimming are considerable. Indeed, they're cited more than the physical effects.

"It's like a pillar of sanity," says Baird, who regularly completes a round trip of about 1.5 kilometres from Manly with the Bold and Beautiful throng, COVID having spread out the swimming times. "People just go all day now."

In Phosphorescence, Baird writes that several Bold and Beautiful friends had ceased taking antidepressants.

Lingham calls the mental health boost for Shrinkäge swimmers "phenomenal", attested to by a "significant number of people in the group".

Camaraderie is also important to his Speedoed troupe. I saw this firsthand at 6am, about 200 metres from shore, when, at Lingham's instigation, our group joined in a rendition of Happy Birthday for one of the Shrinkäge crew.

Whereas salt water might be a placebo, there's science behind the psychological boost. "It's quite good for depression because you get this adrenalin burst," says Murphy.

"It is an endorphin rush … the colder it is, the more adrenalin is released." Murphy posits, too, that ocean swimmers can improve resilience simply by overcoming anxiety and "dealing with the unknown".

Baird also cites the wondrous impact of seeing the marine life. "Something happens when you dive into a world where clocks don't tick and inboxes don't ping," she writes in her book. "As your arms circle, swing and pull along the edge of a vast ocean, your mind wanders and you open yourself to awe … studies have shown that awe can make us more patient and less irritable, more humble, more curious and creative."

In Melbourne's bay, there's less awe on offer, although some of us have felt the mild stings of jellyfish, and December's still and clearer waters have meant small fish were actually visible at Elwood.

What are the health hazards?

If I was slurring my words after the first swim, it's likely that my body temperature was below the recommended minimum and that hypothermia had set in. Murphy says hypothermia can be defined as a body temperature of below 35 degrees.

"One of the contributing factors is you're not taking in enough fuel, you're expending a lot more energy," says Murphy.

Ingesting excessive salt water is another potential issue, she says. It carries the risk of pulmonary oedema caused by too much water in the lungs.

There are, in some waters, sharks and stingrays. Fear of sharks is atavistic – barely a fortnight ago, a swimmer traversing the pier-to-pub course in Lorne on Victoria's surf coast was within metres of a shark, albeit without knowing, but there's been no shark fatality in Victoria for decades.

Jellyfish are abundant in both Melbourne and Sydney and it's worth packing a soothing anti-sting lotion. I've had a couple of stings, one of which caused a very itchy wrist rash. "There's no deadly one," says Murphy.

On foggy mornings, there's also the small risk of swimmers taking the wrong turn and, unable to see the shore, getting lost at sea for a dangerously long period in cold water.

On May 26 a swimmer became disoriented at Mentone, in Melbourne's bay, despite buoys and bright caps, and was unaccounted for by his fellow swimmers for what one called "the most terrifying 40 minutes of my swimming life". The group went to shore, paddled out on boards and, amid thickened fog, eventually found their friend off shore.

"Ten more minutes and it might not have ended this way," writes one of the swimming party on Bay Open Water Swimmers Facebook page.

Rip currents are always something to watch out for. Justin Scarr, chief executive of the Royal Lifesaving Society Australia, has four safety tips for sea swimmers: never swim alone; know your limitations; get a medical check-up before you swim, "especially if you're more than 50 [years old]", and make cardiac health a priority; and consider taking a "buoyancy device'' such as an open-water swimming buoy.

What's next after the sea change?

Lingham calls the sea swimming habit "addictive". He hasn't been in a pool for more than two years and has no plans to return to chlorinated water.

My swimming future is more equivocal. If the pool offers less adventure or gain, it also demands less commitment and affords greater comfort. (You can also swim in a pool after heavy rain without fear of the water being dodgy.) The pool won't be discarded.

That said, I don't see the sea swimming as one those temporary expat-type friendships, forged by isolation and circumstances, that doesn't endure beyond a certain time and place.

The surf, the Aquanauts' next frontier, beckons.

If you want to learn more about the mental and physical health benefits related to open water swimming and cold exposure, feel free to join our ICEWIM Facebook group or follow our Instagram page.

Have you personally experienced a positive impact on your life from open water swimming or cold exposure? We want to hear from you! Share your story with us by emailing an audio or video testimonial to and get a chance to be featured on the ICEWIM Instagram account.

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