New Zealand's underworld, home to one of the world's largest and deepest cave systems. Here, a team of brave divers will attempt a dive that could make history - and push their limits to the extreme.
For anaesthetist and underwater explorer Dr Richard Harris, the allure of the unknown has been irresistible for years. He has spent countless hours exploring the dark passages and tunnels of the Pearce Resurgence cave system, known for its unpredictable currents and lack of visibility.
"It's an intensely intimidating place to be," Harris says in the documentary film Deeper, released this week. "You enter this cave that just seems to swallow you as you go into it. It's black. You come to this abyssal drop which goes over an edge and drops down to 100 metres in depth."
The cave system is not for the faint of heart. Its sheer size and complexity have claimed many lives among experienced divers. But Harris is undaunted, driven by a desire to explore one of the world's most uncharted environments.
"I'm not afraid of it," he says confidently. "I love it. It's an extraordinary world down there."
Harris has already achieved incredible feats in his diving career, including reaching depths of 245 metres and 182 metres without any major incident. But this dive is different - it will test the limits of human endurance and push the boundaries of what is thought to be possible.
The plan is to use a radical new approach - introducing hydrogen as a breathing gas, combined with helium, to help Harris overcome his debilitating hand tremors. This experimental technique has never been tried before, making it a high-risk endeavour.
If successful, Harris will become one of the most elite divers in the world, known for his bravery and willingness to push the limits of human exploration. But if things go wrong - and they could - he risks losing control of his equipment, leading to a catastrophic outcome.
"I'll be fine," Harris says, his voice steady despite the risks involved. "I've spent months researching this technique, speaking to world experts. I'm confident it will work."
But not everyone is convinced. The dive team's supervisor, Prof Simon Mitchell, warns that there are significant risks involved. "There were very significant risks," he says candidly.
The night before the big dive, Harris is filled with anticipation and nerves. He checks his equipment obsessively, visualizing every possible scenario and how he would respond to each one.
Finally, at 5am, he slips into the cold water alongside Challen, a seasoned diver who has been his friend and companion on many adventures. As they descend into the darkness, Harris is filled with an overwhelming sense of calm - it's as if the hydrogen mixture is already working its magic.
At 200 metres, Harris switches to the new breathing gas, feeling an incredible rush of relaxation wash over him. The tremors in his hands begin to subside, replaced by a sense of clarity and focus.
"I felt incredibly relaxed and in control at that depth for the first time ever," he says, his eyes shining with emotion. "I thought, 'Wow, I could just keep going.'"
The ascent is a slow and agonizing process, but Harris and Challen press on, their faces set in determined smiles. They finally break through to the surface, blinking in the bright sunlight as they take in the sight of the world above.
For Harris, this dive has been a defining moment - one that will shape his identity and redefine his limits. He emerges from the water with a sense of pride and achievement, knowing that he has achieved something truly remarkable.
"I shouldn't need to get to the bottom of a cave in NZ to be OK with who I am," he tells the camera, his voice filled with emotion.
And so, for Richard Harris, the allure of the unknown has led him to this moment - one that will forever change the face of deep-sea diving.
For anaesthetist and underwater explorer Dr Richard Harris, the allure of the unknown has been irresistible for years. He has spent countless hours exploring the dark passages and tunnels of the Pearce Resurgence cave system, known for its unpredictable currents and lack of visibility.
"It's an intensely intimidating place to be," Harris says in the documentary film Deeper, released this week. "You enter this cave that just seems to swallow you as you go into it. It's black. You come to this abyssal drop which goes over an edge and drops down to 100 metres in depth."
The cave system is not for the faint of heart. Its sheer size and complexity have claimed many lives among experienced divers. But Harris is undaunted, driven by a desire to explore one of the world's most uncharted environments.
"I'm not afraid of it," he says confidently. "I love it. It's an extraordinary world down there."
Harris has already achieved incredible feats in his diving career, including reaching depths of 245 metres and 182 metres without any major incident. But this dive is different - it will test the limits of human endurance and push the boundaries of what is thought to be possible.
The plan is to use a radical new approach - introducing hydrogen as a breathing gas, combined with helium, to help Harris overcome his debilitating hand tremors. This experimental technique has never been tried before, making it a high-risk endeavour.
If successful, Harris will become one of the most elite divers in the world, known for his bravery and willingness to push the limits of human exploration. But if things go wrong - and they could - he risks losing control of his equipment, leading to a catastrophic outcome.
"I'll be fine," Harris says, his voice steady despite the risks involved. "I've spent months researching this technique, speaking to world experts. I'm confident it will work."
But not everyone is convinced. The dive team's supervisor, Prof Simon Mitchell, warns that there are significant risks involved. "There were very significant risks," he says candidly.
The night before the big dive, Harris is filled with anticipation and nerves. He checks his equipment obsessively, visualizing every possible scenario and how he would respond to each one.
Finally, at 5am, he slips into the cold water alongside Challen, a seasoned diver who has been his friend and companion on many adventures. As they descend into the darkness, Harris is filled with an overwhelming sense of calm - it's as if the hydrogen mixture is already working its magic.
At 200 metres, Harris switches to the new breathing gas, feeling an incredible rush of relaxation wash over him. The tremors in his hands begin to subside, replaced by a sense of clarity and focus.
"I felt incredibly relaxed and in control at that depth for the first time ever," he says, his eyes shining with emotion. "I thought, 'Wow, I could just keep going.'"
The ascent is a slow and agonizing process, but Harris and Challen press on, their faces set in determined smiles. They finally break through to the surface, blinking in the bright sunlight as they take in the sight of the world above.
For Harris, this dive has been a defining moment - one that will shape his identity and redefine his limits. He emerges from the water with a sense of pride and achievement, knowing that he has achieved something truly remarkable.
"I shouldn't need to get to the bottom of a cave in NZ to be OK with who I am," he tells the camera, his voice filled with emotion.
And so, for Richard Harris, the allure of the unknown has led him to this moment - one that will forever change the face of deep-sea diving.
just thinking about Richard Harris's dive into the Pearce Resurgence cave system is giving me goosebumps! The way he pushed his limits and experimented with a new breathing gas to overcome his hand tremors is truly inspiring 
. As someone who's always been passionate about mindfulness and mental well-being, I think it's amazing that he was able to tap into the power of hydrogen to calm his nerves and focus on the task at hand 
. Of course, there are risks involved with any extreme dive, but it's clear that Harris has put in the research and planning to make this endeavor a success 
. Can't wait to see how he reflects on this experience and what it means for his future diving adventures 
he's got hand tremors and uses new breathing gas combo... risks are real tho 
but his calm vibes during the dive had me rooting for him 
while taking a fancy new gas combo 
. Newsflash: if he wasn't, like, totally convinced it was gonna work 
, why bother? And 100m depth is hardly "abyssal" 
. That's like, swimming pool deep for some of us 
. Anyway, kudos to him and his team for making it out alive, I guess 
200m without major incident is already a huge deal, but attempting a dive like this with such radical tech? 
he's either going to make history or get himself into a world of trouble 
and honestly i'm kinda rooting for him to succeed 
just saw the doco on Richard Harris's epic cave dive and I'm still reeling from the bravery 
not many people would dare to take on a dive like that, especially with this new breathing gas experiment 
it's mind-blowing how relaxed and focused he was under the water 
. Either way, I hope everything goes smoothly and he makes history. I'm living vicariously through him 
. fingers crossed he makes it out unscathed