'The Deepest Breath': Riveting, stressful and utterly terrifying freediving documentary

Filmmaker Laura McGann immerses us in the captivating, but highly dangerous, sport of freediving with the documentary The Deepest Breath, following the journey of champion freediver Alessia Zecchini and safety diver Stephen Keenan.

“The deeper I’m diving, the pressure compresses the air in my lungs, until my lungs are the size of my fist," Zecchini says in a voiceover in the documentary, explaining the feeling of freediving.

"After 30 metres, the pressure pushes me down. It’s called the free fall. And this, for me, is the best part. It feels like you are flying. The silence, it’s unique. It’s like being in the last quiet place on the Earth.”

Throughout The Deepest Breath, McGann provides the audience with enough basic information about freediving, while also exploring this world like a love story.

As the narrative evolves, it's about the love these freedivers have with the ocean and the sport, and the love they have for each other. That's all paired with mesmerizing visuals of the ocean.

The Deepest Breath begins with a significant amount of archival footage, getting to know Zecchini and Keenan and understanding why they gravitated towards freediving, largely told by their fathers, Enzo and Peter.

But the documentary takes a turn when it shines a light on the psychological and physical challenges of freediving, and the associated risks, with harrowing footage of divers "blacking out" as they approach the surface.

“Getting sucked to the bottom of the sea can be scary, even for freedivers," journalist and author Adam Skolnick says in The Deepest Breath. "You have to break this deep meditation because coming back to the surface, that’s when the work really starts."

"You’ve got to swim the length of a 70-storey skyscraper. … Your oxygen supply's already dwindled. You’re kicking hard so your heart rate’s increasing, burning that oxygen quicker. You’re now getting to the point where you don’t have enough oxygen to keep the systems going. That’s why you can have a black out.”

As freedriver William Trubridge explains, blacking out is essentially when "the brain basically turns itself off."

"It’s kind of like a safety mechanism," Trubridge says in the documentary. "The brain preserves itself by shutting off all its functions."

"From that moment, you still have one or two minutes before brain damage would start to occur. If you don’t have the right kind of medical attention, it can go downhill pretty quick. It’s definitely not something to be taken lightly."

As we learn in the film, Keenan's path to becoming a safety diver began after he experienced a significant black out.

Keenan and Zecchini met during a Vertical Blue competition in the Bahamas. As it's simply put in the film, Zecchini had a problem with the dark, but she was able to work past that after training with Keenan.

The pair continued to train together beyond that competition, until we get to the big moment documented at the end of the film.

While this is a story of true events, meaning you can very well find out about these two individuals with a quick search online, McGann is also teasing the ending throughout the film (which we won't entirely spoil for you here). More impressively, even if you know what happens, it still feels like your heart is sinking to your stomach in those final moments of the documentary.

While McGann strings together a beautiful collection of images, it's the simple sounds of heartbeats and the more silent moments in the film that really pack a punch, making you both terrified but glued to the screen.

The Deepest Breath is in select theatres July 14, available on Netflix July 19