There's a serenity in the silence under the water.
The free diver, Michaela Werner, glided close to the bottom of the pool, taking long steady strokes. She swam the entire length of the 25-metre pool underwater, before coming up for air for less than 10 seconds at either end. In that short time, her coach might give her the lap count before counting down from seven, six, five, four, three ...
He might offer a focus word - 'gratitude', 'compassion', 'grace', 'smoothness' - that Ms Werner can hold and draw all her attention to for the next 10 laps. As she comes up for air, she has a mere few seconds to take a few deep, forced breaths - expelling the accumulating CO2 from her body and taking in as much oxygen rich air as she can - before plunging back under the surface.
Free divers spend countless hours training their body not only to survive on ever dwindling oxygen, but also to remain calm with the gradual build up of CO2 as they spend longer and longer under water without the aid of breathing apparatus.
On Friday, at Charlestown, Ms Werner, 44, set out to break the world record for underwater swimming by completing 100 laps of the Swim Centre pool - a cumulative distance of 2.5 kilometres - in under an hour.
She was equipped with only a wet suit, a pair of goggles, and a weight that sits over her shoulders to help her regulate her position in the water column.
"It's my superpower," Ms Werner said, after stepping out of the pool. As she completed her last lap, with more than a minute to spare, she plunged a final time to add one more to the record before her family leapt in to celebrate. "I feel very comfortable under the water, in the ocean, holding my breath.
"I imagine I'm a fish or a whale. It can feel supernatural. You literally leave everything up on the surface and you dive, not only to look around, but to look inside. There is no sound, no noise, no phones; all you have is yourself - the present moment - and it's just an incredible experience.
"I'm just lucky enough that I found my superpower in my lifetime."
Ms Werner has been free diving for more than 15 years, travelling the globe, and around the country. As she conceived of the world record attempt, she wasn't sure if it would be possible, but as the laps tumbled in her wake, she found herself with that familiar feeling of going inwards.
At the end of the pool, Queen played through a small portable speaker.
"I did have some music there but, to be honest, I just went inwards. I was trying to realise how special it is that I'm even doing this and just observing my body. I didn't look sideways once."
As the final laps fell, Ms Werner's friend and fellow free diver Jordy Duncan - the Australian women's champion - leapt into the pool to swim the final 500 metres. The pair met in competition and as the record was secured, Ms Duncan was there to celebrate the achievement.
"She was maintaining about 22.5 seconds underwater," Ms Duncan said, "For someone who doesn't have a swimming background, it could be quiet challenging - it's not that far under the water, but (after 100 consecutive laps), it is a long time that you have to stay mentally focussed.
Ms Werner had been undergoing strength training and running to help her prepare for the feat, but Ms Duncan said her mental fortitude was a true testament of her ability to remain calm and centred as the oxygen levels dwindled.
"She is very good at that. She can just stay present rather than thinking ahead. It's just as physical as it is mental."
Ms Werner's husband, Jochen, and their three children, Kristina, Thomas and Lukas were poolside on Friday, cheering her on as they set out to raise $10,000 from the world record attempt, with all money going to Take 3 For The Sea, a non-profit Australian organisation aiming to rid the oceans of plastic pollution.