It's easy to look at Adam Stern and decide freediving is not for you.
Descending 93 metres into an underwater trench and having to hold your breath for six-and-a-half minutes isn't for everyone.
At least that's what many people think.
"The average human walking on the street can actually hold their breath between four and five minutes before they're unconscious," Adam says.
"Sometimes freediving has this perception of being this really big terrifying risky thing because they've seen videos of people diving 100 metres underwater.
Despite growing up on the shores of Copacabana on the Central Coast, Adam didn't try freediving until a backpacking trip around Thailand when he was 21.
"Because you have no idea what a great freediver you already are, you go and do it and feel like you've discovered a superpower. Like, I can do this incredible thing that I didn't know existed," Adam says.
"People tend to, when they get into it, tend to identify as freedivers very strongly."
Now Australia's freediving record holder, the "Sea Lord" as he's sometimes referred to, teaches people from across the world on his Deep Weeks — a week-long "freediving festival slash learning event".
With the sport growing in popularity, mums, tradies and school leavers often sign up for the courses.
"Most people after a day or two diving are pretty comfortable diving between 10 and 20 metres," Adam says.
"My job is to sit there while they do the thing they can already do."
Overcoming the urge to breathe
Kate Borysuk thought she could barely swim, let alone freedive.
"I'm from a city in a very cold part of Russia," Kate says.
"The first time I saw the ocean I was 25 years old … I was terrified."
Since moving to Australia six years ago, she's slowly tried to overcome her fear of the water.
She started with scuba diving. Which was terrifying.
"It was hard because it was very scary and I'm quite an anxious person," Kate says.
When more of her scuba friends turned to freediving she signed up for a Deep Week.
"Going out there without a tank or oxygen was unbelievable, I did not want to do that," Kate says.
Over time, and another Deep Week, she learnt to lean into that anxiety.
"I kept remembering all those things that I've been taught about my own body, and what my body does and what it can do, and what I've already done, and how much potential we have," Kate says.
"Yes, contractions come. Yes, it's kind of scary, Yes, we're deep. Yes, we kind of need to breathe.
"But also it's fine, it's OK. That's how it's supposed to be and it's great that you feel this way because you understand what is happening with you.
"They break it down to the very tiniest detail."
After three years of freediving, she has no fear.
"Eventually for me, it became a bit of a switch that I can just flip and I'm relaxed. I'm more at peace with myself," Kate says.
"Maybe it's a bit choppy and rocky, maybe it's raining and grey, maybe it's a new place but because I have all this knowledge and skill I'm not afraid.
"What do I do when I go diving? I start breathing calmly, slower. I go through my body scan, I'm looking at my body and listening to it. What's not relaxed right now, what is very tense?"
Not that she really has a choice.
"If you don't relax, you can't dive deep," she says.
Is it dangerous?
The urge to breathe that Kate refers to is what Adam and his instructors teach their students to listen to.
"Your body tells you when to breathe," Adam says.
"You're not going to fight the urge to breathe, that's your body's natural mechanisms. You listen to that and respect that.
While the odd incident does happen, Adam says freediving is the safest extreme sport in the world.
"It's because your body is a much better machine than the breathing apparatus that we made to take people underwater," Adam says.
"Diving deep feels good. Diving deep is not hard.
"If a dive is challenging or doesn't feel good, you won't physically be able to do it."
Facing up to your life
Unlike Kate, Deep Week instructor Mounir Terfas always thought he was pretty good at managing stress and anxiety.
"I was actually good at distracting myself and not managing it," Mounir says.
"When we talk to elite freedivers who dive 100 metres or more and ask 'what's the difference?' They say relaxation. There's deeper and deeper levels of relaxation."
"Moon" as he's affectionately known, took up freediving to improve his breath-hold for spearfishing and surfing.
"I started realising that there's a whole world to it. Surfing and spearfishing became very secondary," Mounir says.
"I work in corporate life so it can be very stressful, very high energy and it can be draining.
"Doing this again and again allows me to manage my corporate and work life better."
His love for freediving and the community it has provided him convinced Mounir to give up a place at Massachusetts Institute of Technology (MIT) in Boston this year to stay in Australia.
The sea is a bit easier to access from Sydney's northern beaches.
"Again and again I'm training my brain to be OK with [everyday] conflict. But also to be able to shift away from stress and use it as a good thing rather than be subject to it," he says.
