Before I tell you anything about myself, I want you to experience something.

Right now, something ancient is happening inside you. Your heart rate is slowing. Your body is redirecting blood away from your limbs toward your brain and your heart. This is called the mammalian dive reflex — a survival mechanism hardwired into every air-breathing mammal on earth. Seals, dolphins, whales — and you.

Your life was defined by your first breath — as you inhaled. It will end with your last breath — as you exhale. And the quality of your health, and your life, is defined by the quality of your breath in between.

When you've spent 25 years teaching people to go into an environment where you cannot breathe, your relationship with breath gets interesting. I'm Sacha Williamson — founder of Freedive Aotearoa, New Zealand's first dedicated freediving school. I teach people to hold their breath, feel comfortable, and dive as deep as they want to go into the ocean. But I didn't start here.

Chapter One

One of the First Women in Australasia to Work as a Commercial Diver

Way before any of this, I was one of the first women in all of Australasia to work as a commercial diver — building things underwater for a company called Undersea Construction.

It doesn't matter if you're a five-foot-five petite woman or a seven-foot, 120-kilo man — you're not moving the structures that are underwater. Everything is enormous. Chain links the size of your body. Ten-tonne mooring blocks. So you learn very fast: you've got to think smarter, not harder. Figuring out how to solve impossible problems underwater — quickly — became something I was good at.

Chapter Two

The Story That Shows Who You Really Are

In 2001, the Australian government began what was called the Pacific Solution — intercepting asylum seekers at sea and sending them to tiny Pacific islands for processing. One of those islands was Nauru — a speck in the Pacific. 21 square kilometres. Almost no infrastructure.

I was sent there as a diver, to help put in a desalination plant so there'd be water to drink. But remote islands have a way of sorting people out fast. I ended up doing two jobs: building a harbour so goods could be brought off container ships, AND installing the desalination plant. And somewhere along the way, I became an explosives pattern blast designer.

I remember one morning we were meant to pour concrete. The brand new concrete truck was missing. I followed island whispers around to find it — and overnight, the tyres had been borrowed. The locals had taken them to use on something else. I'm now looking for the tyres, and the driver, in three different places across the island. Put it all back together. And then start the job.

Chapter Three

45 Countries. Most of Them by Boat.

From Nauru, the work kept coming — through AusAID, the United Nations, the Department of Conservation, NIWA. Installing infrastructure in places that had none. Training diving instructors for nearly two decades. Working alongside university researchers nationally and in remote islands. Setting explosives underwater, which is far more exciting than it sounds.

I've been lucky to travel to some of the most incredible dive sites globally, reaching over 45 countries by boat. And I want to be honest — it hasn't always been glamorous. I've crossed oceans where the seas were so savage they turn brave men into cowards. I've outrun pirates. I've been shot at off the coast of Colombia. Bribed my way through corrupt ports. Swapped cheap alcohol for black pearls. Dived some of the most magical places on earth. And fled countries where staying one more hour would have been a very bad idea.

I owe all of this to my father — an incredible captain, diver, and adventurer. The kind of man National Geographic would hire to take them to Antarctica. Extreme expeditions were just normal behaviour in our family. He never once told me I couldn't do something. If there was a job to be done, all hands on deck.

Chapter Four

The Strangest Doors

For all of that — the only time I've ever been credited with anything close to 'fame' is when I became, affectionately, New Zealand's Mermaid. I have three daughters. So naturally, mermaid tails appeared in my life. And somehow I ended up on the radio, on the front cover of magazines, on The Morning Show, in a costume, talking about being a mermaid. Which, for the record, I had never actually been.

I could have been offended by that. All those years of serious, dangerous, technically demanding work — and the world wants the mermaid. But here's what I've learned: life opens the strangest doors. And the mermaid tail opened doors that my dive certificate never could.

The last time I was on Nauru, I was four months pregnant with my eldest daughter. And that was it. The insurance wouldn't cover me. The lifestyle didn't suit. I lost my career the moment I became a mother.

But something else grew in its place. A softness. A slowness. A femininity I hadn't had room for before. And in that quiet space, my desire for freediving grew. Commercial diving is machinery, noise, equipment, brute force. Freediving is one breath. Stillness. Going inward. It matched who I was becoming.

When my eldest two girls were three and four, I took them to Indonesia and started teaching freediving. These two worlds — motherhood and the ocean — were the first things in my life that could live harmoniously together. I didn't have to choose. The hard skills got me here. But freediving — that was coming home.

Chapter Five

The Oldest Form of Diving on Earth

From the outside it looks wild. One breath, deep water, no tank. But from the inside, it's the opposite. It's the quietest, stillest thing I do.

Freediving is ancient. Long before scuba tanks existed, humans dived on a single breath — for food, for pearls, for sponges. The Haenyeo women of South Korea have been doing it for centuries. The Sama-Bajau people of Southeast Asia have dived this way for so long that their bodies have actually evolved — their spleens are larger, they hold more oxygen. Freediving isn't new. We just forgot it was ours.

What I teach is simple: how to breathe properly, how to relax in water, and how to trust what your body already knows how to do. That mammalian dive reflex you felt — that's your body saying: I remember this. My job is to help you listen to it.

It doesn't matter whether you come to me in a wetsuit or a mermaid tail. The breath is the same. The calm is the same. The ocean doesn't care what you're wearing.

Chapter Six

Everything, Poured Into One Place

Everything I've learned — from commercial diving, from the Pacific, from 25 years of teaching — I've poured into Freedive Aotearoa, right here in the Bay of Islands. The business runs on three pillars:

But the work I'm most proud of is what we're building for young people. I've spent years delivering ocean education programmes in schools across Northland — with the R. Tucker Thompson Trust, with conservation organisations, in hundreds of school programmes. And now I'm working on a structured career pathway so that a young person in Northland can actually train as a professional freediver and instructor through the education system. That pathway doesn't exist yet in New Zealand. I want to build it.