Sampson Ward was bored with swimming in "ocean baths and granny pools".
Following the long black line end-to-end was one thing, but he was looking for a new challenge.
That is how he found out how long it takes to swim five kilometres in Throsby Creek.
Ward, an 18-year-old former competitive swimmer, is one of at least two Hunter swimmers to have courted the attention of the algorithm in recent months, posting recorded swims in ponds, fountains, creeks and golf course water traps to social media.
"Swimming in ocean baths and granny pools was getting a bit boring," Mr Ward said when asked what inspired the leap into murkier depths.
"So, I thought, why not take it to where someone is going to watch it and think what the heck is this guy swimming in?"
He certainly got the expected reaction on social media.
"Did the flu shot this year work?" wrote one commenter on Mr Ward's latest swim in a Sydney fountain.
The potential health risks in taking a dip have not daunted the swimmers.
Sean McCabe, another swimmer, has been posting similar videos in fountains and golf course ponds around the region.
Laps in the Civic Park and Customs House fountains, among other not-so-idyllic waterholes including the fountains outside Maitland City Library and Erina Plaza, have collected sizeable view counts.
Attempts to contact Mr McCabe, 20, went unanswered, but he said in a post shared on his social media accounts that he had started making the videos as a social anxiety salve.
"My feet were dragging along the ground most of the time," he said of swimming in the Customs House fountain, before commenting on Mr Ward's posts, labelling him a "copycat".
The rivalry between the social-media posting swimmers appears to be spreading - from swimming to similar endurance stunts
Five-kilometre road trips, recorded entirely at the King Street McDonald's drive-through, were also in the works, Mr Ward said.
While he said his swims were often improvised in the moment, Mr Ward was happy that the capers were shedding light on the quality of the city's creeks and streams.
"People dump stuff in there, not being considerate," he said. "It's a creek. You should be able to swim in it."
Professor Ravi Naidu, the founding director of Newcastle's Global Centre for Environmental Remediation, said the drainage systems that run through the Tighes Hill area in particular risked potential contamination from road and residential runoff, as well as from the surrounding industrial areas.
"From a precautionary public health perspective, swimming in urban drainage systems would generally not be recommended due to the potential exposure to contaminants and pathogens, especially through accidental ingestion, skin contact, or contact with open wounds," he said.
A three-year study that concluded in March found Throsby Creek had the state's fifth-highest concentration of microplastics.
Hunter Water, which has been monitoring the quality of Throsby Creek since September with state government funding to better understand the creek's health, advised when the project began that residents should be careful when coming in contact with urban waterways.
"Throsby Creek is a much-loved part of our city, and we know the community wants to see it thrive," the utility's waterways general manager David Derkenne said in September.
He added that the monitoring program, which set out to collect 100 unique data points from microbial water quality tests by June this year, would deliver a "clearer picture of the creek's condition and the actions needed to support safe and sustainable use into the future".
