Having already ticked off the English Channel, Brenda Norman and Richard Jones have now set their sights on more frigid water, the Ice Mile.
They are part of a broader group of friends called the COWS.
The Camperdown Open Water Swimmers are fearless, fit, highly successful professionals who are addicted to long-distance swims in very cold water.
It is 7:00am, the icy midwinter wind blows across Lake Bullen Merri in the still-dark dawn, and a group of rugged-up friends are gathering to undress by the boots of their cars.
The unofficial group leader, Rod Watkins, wears a fluro pink swimming cap with his down jacket, jeans and sheep-skin slippers, as do his peers.
He is the first to bare his skin to the bracing weather, revealing a pair of bright pink psychedelic togs.
On this occasion, the swim is in a very large, cold lake, a volcanic crater filled with freshwater that is currently reading ten degrees Celsius.
"This lake is actually two craters that are two volcanoes. So when you look at it from the top, it looks like a cloverleaf," Mr Watkins said.
Rod and Alison Watkins operate a cattle and cropping property, splitting their time between the city and their farm in Bookaar, which is where they ended up during Victoria's long COVID-19 induced lockdown.
"The COWS were formed as a bit of a COVID creation, actually," said Mr Watkins.
"A group of friends started swimming down here during summer when it was considerably warmer than it is this morning — and it's continued."
Friends, with the English Channel in common
By day, Alison Watkins is the Chancellor of the University of Tasmania and Director of the Reserve Bank of Australia.
She said sitting on the Board of the Reserve Bank is far less nerve-racking than today's swim, which is going ahead despite a turn in the weather that has made conditions unsavoury.
"I'm much more nervous about this swim. I can tell you that," she said.
"Really, I've just been tagging along after Rod. He's a very accomplished swimmer. He's done the English Channel and a range of other huge swims," Ms Watkins said.
In this group, having swum the English Channel is a common interest — three of them have done it.
Astonishingly, the English Channel was not even Mr Watkins' longest swim. He's also swum around Manhattan Island, New York City, which is an unimaginable 54-kilometre marathon.
The ice mile
Having completed the English Channel, and unable to travel, Brenda Norman and Richard Jones have been looking for a new challenge.
Together with Sue Jones, the trio is in training for a race alarmingly called 'The Ice Mile'.
"It's a swim that needs to be in water less than five degrees [Celcius]. And then obviously, it's one mile. So 1.6 kilometres," Ms Norman said.
"I've never actually been in water that's under five degrees, but a lot of stuff I've swum in is seven.
If you were wondering why people would want to participate in such a race, they said it was partly the adventure and opportunity to meet others who similarly go at life "hammer and tongs".
But it was also about the addictive quality of the vitality it gives them, despite the strange effects that prolonged submerging in cold water has on body and mind.
Addicted to that buzzy feeling
Sue Jones has been training in cold water for a while and has observed her body becoming used to it.
"The circulation system becomes so efficient," she said.
"It goes, 'Uh-oh, she's doing it again', and it shuts down really quickly. So you find that the cold water has less and less of an effect. I'm swimming much further than I did last year and not drowning" Ms Jones said.
Even so, after a while, the body does become hypothermic and the swimmers observe it shutting 'unnecessary' areas down, mid-swim.
"As you become more hypothermic, you become dissociative, which is weird: People I know on an associative level — I can't remember their names until I warm up again," she said.
Despite all of this, Ms Jones reported a remarkable, life-affirming increased health in body and mind since she has been open water swimming.
"I haven't had a cold in five years," Ms Jones said.
"It improves optimism. It has a really positive effect on mental health.
The youngest member of the COWS, Lachlan Wilson, said he was addicted to the euphoria that cold water swimming gave him.
An investor living in Melbourne Lachlan was a Brighton Iceberger before relocating to the Camperdown area to wait out COVID on his family's farm.
"COVID had a whole range of impacts on our lives," Mr Wilson said.
"And one of the really, really incredible outcomes of COVID was the sense of community we were able to create down here, with particular reference to the swimming club," he said.
"The rush that you get after swimming is a tiny bit analogous to what you might feel if you have a little bit too much to drink, for example, you know, it's that elevated feeling of emotion," Mr Wilson said.
"Having said that the difficulty of hopping in the water never stops. It doesn't get any easier."