He dodged crocodiles, stingers, ships, and large tides in tropical seas on his last distance swim.
But now Darwin resident Michael Wells is going to try something unthinkable — swimming in a chilly New Zealand lake under snow-capped peaks.
And his coach says the temperature difference will be the biggest hurdle.
Mr Wells is going to brave the chilly 21-degree waters of the North Island's Lake Taupo and attempt to be the first to breaststroke 40.2 kilometres across New Zealand's biggest lake.
In June 2018, he swam 6km across Darwin Harbour.
"What could possibly go wrong? There are no crocs, stingers, large ships, or tidal movements," he joked.
"But the answer is exhaustion, exposure, and possibly hypothermia and all in that order".
Did he lose a bet?
Kind of. Taupo was more of a dare.
"I had a colleague who went to New Zealand after my harbour swim and she saw some information about the Lake Taupo swim," Mr Wells said.
"She sent me a message saying: 'Haha, Michael. This could be your next challenge'.
"It's 40km and nobody had done it until 1955 and not many have done it since.
"There are various records associated with this swim. I thought maybe I could be the first to do it breaststroke."
And the holder of some of those records is Mr Wells' coach — legendary New Zealand swimmer and Taupo expert Philip Rush.
"There is still snow on the hills," Mr Rush said.
'Hypothermia is a real risk'
"The air temperature is lower than he's used to," Mr Rush said.
"He's quite comfortable, it's a matter of extending that out for the next couple of weeks so he's got good distance in the cooler conditions.
"It's not a natural temperature of him. That will be the main thing for him to worry about."
While few might not have much sympathy for a swimmer leaving the steamy waters of Darwin for colder climes, Mr Wells is concerned about the sea change.
"The [water temperature] is only 21 degrees, so hypothermia is a real risk," he said.
He's timed the swim for the weekend of February 8 and 9 when the water will be at its warmest.
But isn't that just after the traditional Christmas fattening period?
"For an endurance feat you're using your body fat for that," he said.
"You can be slightly overweight and middle aged and an elite athlete at the same time."
But why breaststroke?
Both of Mr Wells' swims have been fundraisers in memory of his sister, Susan, who died of breast cancer in March 2017, leaving husband Colin and 12-year-old son Gabe.
"It's in memory of her and women like her who have to live with this terrible disease," he said.
"My sister had a special affinity for New Zealand.
"I have a knack for breaststroke and I'm not very good at freestyle.
"I think the reason nobody's done breaststroke is that it takes so much longer."
Mr Wells, who works as the director of the NT Government Heritage Branch, has done his historical research on big swims and the lake.
Mr Rush, who set the standing 10-hour, 14-minute crossing record in 1985, confirmed that breaststroke was not the swim of choice for distance lake swimmers.
"Nobody's ever attempted that before," Mr Rush said.
"Breaststroke is a huge challenge and I think Michael is up to it."
But why … why?
"It's like Mount Everest — because it's there," Mr Rush said.
Mr Rush is the keeper of accurate records for swimming in the lake. Twenty-three people have swum the lake to date, but all swam freestyle.
"We've challenging weather conditions and water temperatures," he said.
"You do it to beat that piece of water that you're up against and achieve.
"I think I'm quite normal but other people tell me different."
How do you survive a full day of swimming?
Mr Wells is undergoing four weeks of training at Taupo and has spent each day for months staring at the black lines at the bottom of Darwin's swimming pools.
Wearing nothing but trunks, he estimated a 3:00am start to touch the ground again about 16 hours later at twilight.
He'll hydrate and feed on sachets of energy and carbohydrate gels.
But he's not allowed to rest to make a record.
"I don't think I'm mad. People thought I was mad when I planned to swim across Darwin Harbour," he said.
"If other people have done it, then I can do it."
Funds raised for the Swim for Susan — Aotearoa challenge go to the National Breast Cancer Foundation.
