In Avatar: The Way of Water, protagonist Jake Sully and his forest-dwelling Na’vi family exile themselves to Pandora’s atolls, where the Metkayina clan lead much of their lives underwater. At first, the newcomers struggle to hold their breath long enough to join in. But with a little practice, the Sully family learn to spend many minutes underwater, long enough to escape giant sea creatures and swim with the whale-like tulkuns.
To achieve its high level of realism, the movie includes many scenes shot entirely underwater — which meant the cast and crew had to learn to hold their breath, too. In fact, they trained for months with elite freediving trainer Kirk Krack. During one session, Sigourney Weaver reportedly held her breath for over six minutes; Kate Winslet broke a movie record at seven minutes and 15 seconds. As someone who has engaged in their fair share of recreational pool breath-holding competitions, I couldn’t imagine lasting seven minutes, let alone one. But according to breath-hold experts, most people can learn to go without oxygen for far longer than they’d think.
Without any training, the average healthy person has the ability to hold their breath for around two minutes, Nick Fazah, freediving instructor and co-owner of East Coast Divers in Brookline, Massachusetts, tells Inverse. In just an hour of training, Avatar’s Krack told me he could probably get me to four minutes.
So if anyone can do it with practice, what makes holding your breath so challenging at first? New breath holders often get stymied when they feel like they’re out of breath. That scary feeling — aptly termed the “urge to breathe” — is a natural and inevitable part of a breath-hold. When you hold your breath, the concentration of carbon dioxide in your bloodstream rises, sending a signal to your brain to inhale. Once that urge to breathe arrives, it doesn’t leave. After about two minutes in an untrained person, the diaphragm contracts in an attempt to force a breath, leading to full-body shudders.
This contraction is considered to be a physiological breaking point, the moment when the urge to breathe usually takes over, and you swim to the surface. But it’s not inherently dangerous, and it doesn’t need to be the end of the breath-hold. In fact, elite freedivers can hold their breath through as many as 75 contractions. The trick is simply to ride it out.
“As that urge to breathe begins to climb, I just become further and further introspective,” says Fazah. “I'm going to acknowledge [the feelings], but I'm not going to react.”
If that sounds like meditation, that’s because it’s not far off. Freediving requires an intense presence of mind. “All of this other shit that I'm normally thinking about… it has to go away,” he says. “I have to just be here.”
Breathing and relaxation exercises alone can stretch a person’s breath-hold game by several minutes. But with practice, the body starts to adapt, too. It begins to tolerate higher levels of carbon dioxide, pushing back the arrival of the urge to breathe and those gnarly respiratory contractions. (Fazah doesn’t get contractions now until the three-and-a-half-minute mark.) The body’s diving reflex, a physiological response that reduces heart rate and redirects blood flow to the brain, becomes optimized.
Training over time can also increase most people’s total lung capacity, which is the volume of air in the lungs after an inhale, Frédéric Lemaître, who studies the physiology of freediving at the Université de Rouen, tells Inverse. Lungs contain some amount of air that the breather can’t access, called “residual volume.” Strengthening respiratory muscles helps reduce that residual volume while also increasing the total lung capacity. That allows freedivers to carry and access more air to stay underwater longer.
“Almost any persistent person who decides to train regularly for a certain period of time can become an elite freediver”
Still, even at the advanced level, freediving is more of a psychological challenge than a physical one. “Almost any persistent person who decides to train regularly for a certain period of time can become an elite freediver,” national Croatian freediving coach and apnea researcher Ivan Drvis told Inverse in an email.
Past the psychological level, things can start to get dangerous. The urge to breathe and the diaphragm contractions typically force the body to inhale long before there’s a real problem. Ignoring those warning signals makes the person susceptible to low oxygen, also known as hypoxia, which can lead to a blackout. To further complicate things, just before blacking out, that extremely uncomfortable, suffocating feeling goes away. This sudden lack of discomfort can lead to what some freedivers describe as a “euphoric feeling” that can make it hard to respond appropriately in dangerous situations. “Freediving should be this thing where the beginning of the dive is easy, and then it's work,” says Fazah. “If you get back into easy, that's where it becomes problematic.”
That’s why experts emphasize that it’s extremely important to always train with a partner. It’s also why hyperventilating before a breath-hold is a bad idea, even though it feels like you’re filling your lungs in a helpful way. In reality, rapid shallow breathing decreases CO2 levels. While that will reduce discomfort, it also means oxygen will be your limiting factor instead of CO2 — and that’s much more dangerous.
A safer way around the discomfort of carbon dioxide buildup is to breathe pure oxygen or a nitrogen-oxygen mixture (nitrox) from a tank, which provides additional oxygen for the dive. That method — called technical freediving — is what Krack used with the Avatar cast and crew. Between takes, the actor would breathe on nitrox while Cameron gave notes for the upcoming shot. Then, when the actor was ready, a countdown clock began. As many as 300 people in the film crew waited for the actor to complete a “breathe-up” — a few minutes of slow, calm breathing to prepare for the breath-hold. Once they dove, shots could last two minutes or more in giant water tanks reaching depths of 30 feet.
Given the training and the hit of nitrox, Lemâitre was not incredibly impressed with Winslet’s seven minutes underwater. (I’m still impressed.) If you want to try your hand at the Metkayina way, experts say it’s extremely important to train with professional guidance for safety reasons. Luckily, there are plenty of local freediving courses around, so you too can swim with the tulkuns — if only they existed.
