It takes a certain kind of person to be a free diver. All need not apply. Not everyone wants to plunge into the blackness of the ocean without oxygen, pushing the limits of the human body, swimming what is essentially the height of the Statue of Liberty twice, once down, once back up. These people are “built different,” as they say, and, similar to big-wave surfers or any athlete devoted to extreme sports, are not afraid of the things most humans fear. They run towards the limits. Life-or-death risk is built in.

Laura McGann’s documentary “The Deepest Breath” profiles Alessia Zecchini, an Italian free diver determined to break the world record, and Stephen Keenan, a skilled safety diver (who accompanies the free divers partway down, to help in case something goes wrong). “The Deepest Breath” is a visual stunner, with intimidatingly beautiful underwater photography showing tiny humans surrounded by the vast underwater world, a forbidding space of blues moving into blacks. The visuals give you an awe-inspiring and terrifying idea of what these people experience, what they seek and crave. The pursuit is psychological as much as it is physical. Former world champion free diver Natalia Molchanova said in an interview, “Mental relaxation is the foundation of free diving.” The sport requires you to empty yourself of everything except in-the-moment consciousness. Anything else takes too much energy.

“The Deepest Breath” introduces us to Zecchini and Keenan on alternating narrative tracks. From Italy and Ireland, respectively, Zecchini and Keenan had very different life trajectories: one was driven to be a free diver from a very young age, and the other spent his youth wandering the world, searching for something, but he didn’t know what exactly. Keenan then discovered free diving and was instantly hooked. Zecchini and Keenan are heard in voiceover in interview and podcast clips. The past tense used by other interview subjects shows where this is going (in case you aren’t up to speed on the real-life events).

Zecchini was inspired as a child by the example of Molchanova, whose feats remain legendary, who set records not broken for years and years. Zecchini was still in grade school when she decided she wanted to be a world champion. In 2015, Molchanova disappeared during a dive off the coast of Ibiza. She went down and never came back up. Shockwaves reverberated through the freediving community. Zecchini realized, for the first time, she could die doing this thing she loved. This tripped her up mentally. She said, hauntingly, in one interview, “It’s black. It’s dark. You feel locked inside.” 

Zecchini was so ambitious it made her tense and temperamental. She pushed herself too hard. Even other free divers thought so. But then, in 2017, during a competition in the Bahamas at the Vertical Blue, Zecchini met Keenan in his capacity as a safety diver. He offered to train her after Zecchini blacked out on successive dives. She flourished and broke a world record three days later (102 meters). The following day, her record was broken by Japanese phenom Hanako Hirose (103 meters), which pushed Alessia to break Hirose’s record the following day (104 meters). This triumphant experience solidified the bond between Zecchini and Keenan. “The Deepest Breath” is also a love story.

The pressure of the deep ocean is hell on the human body. Divers risk brain damage and permanent lung damage. There is something called a “lung squeeze,” and you really don’t want it to happen to you. Divers often black out underwater and must be rushed to the surface by the safety divers. CPR is administered while everyone is still in the water: there’s no time even to haul the diver up into the boat. There is traumatic footage of the moments when divers re-emerge to the surface, and they flail, their faces and bodies frozen in a full-body seize. Free divers wear wet suits and monofins, making them look like superhero mermaids as they undulate into the black. The pressure pulling divers down is called a “free fall.” Divers say it feels like flying.

McGann pulled together as much extant footage as possible from the various competitions, plus Zecchini and Keenan’s video recordings, video blogs, Instagram stories, etc. They documented their lives. Other free divers weigh in, and there are some conventional “talking head” interviews, particularly with the fathers of both Zecchini and Keenan, pained men who had to let their children go, who had to let them pursue this very dangerous thing, incomprehensible to most, but essential for the happiness of their children. Since free divers are followed by a hearty talented group of underwater cinematographers, there is existing footage of many of the dives. There are many famous spots free divers gravitate towards, the “vertical blue” in the Bahamas and the terrifying “blue hole” in Dahab, Egypt, with its deadly “arch.” The arch is the most dangerous place on earth for a free diver (“More dangerous than Mount Everest,” says one of the free divers). If you can make it through the arch and back up, you stand with the greats.

“The Deepest Breath” is haunting and eerie in tone, with hair-raising shots of divers swimming down down down, their bodies moving in one continuous rippling motion until they disappear into the blackness near the bottom. Zecchini and Keenan are almost otherworldly underwater, but topside, they are down-to-earth and fun-loving, free-spirited, and wild. Each found a kindred spirit in the other. Free diving is such a small community. When something happens to one, it happens to all.

Molchanova described what it was like at such a depth: “It’s like being in the last quiet place on earth.” Eloquent and moving, “The Deepest Breath” shows what it’s like “down there,” why people risk their lives to free fall into the blackness where it is so quiet, and why they also risk their lives to bring divers in trouble back up to the noisy surface. 

On Netflix now.