Last Breath: What Is Saturation Diving? Everything to Know
Before Last Breath hits theaters, let's take a closer look at the dangerous diving technique behind the film.
This weekend, Woody Harrelson, Simu Liu and Finn Cole play saturation divers in Last Breath, a thrilling deep-sea thriller based on the true story of a 2012 accident in the North Sea. It's a story of courage, a race against the clock, and what it takes to do one of the most dangerous jobs on the planet.
But before you see Last Breath, you might be wondering: What is the "saturation diving" technique used by the divers in the film? What makes it so dangerous, and how can things go wrong? Let's take a closer look.
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What is saturation diving, as depicted in Last Breath?
To do any kind of underwater dive, a diver must be supplied with breathable gas, a mixture that includes oxygen but also inert gases like nitrogen. These gases saturate our muscle tissues, which then dissolve them over time, but the deeper a person dives and the longer they spend submerged, the more those gases saturate their body under pressure from the surrounding water. If a diver comes up too fast, those gases will decompress all at once, creating the painful and even deadly illness known as "The Bends." So the deeper you dive, the longer you need to gradually decompress, so your muscle tissues can naturally deal with the gas.
"Saturation diving" is so named because the divers who do it operate at such depths, sometimes as deep as 1,000 feet, and for such a long period of time that the gases fully saturate their muscles. This means that decompression can take days, or even weeks, under carefully controlled, professionally supervised conditions. Therefore, saturation diving is usually only undertaken by people who do deep sea construction and maintenance work on things like pipelines. It's dangerous, time-consuming, and requires constant attention to detail. It also means living in a state of strange isolation.
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You see, because decompression from saturation diving takes so long, divers don't just stay in their suits underwater the entire time. An entire isolated life is built for them, including a specially compressed chamber that's usually contained inside a ship or an oil rig, diving bells that take them down to the sea floor, and umbilical lines that feed heliox (the combination of helium and oxygen used for saturation diving to prevent an oversaturation of nitrogen) into their suits.
Once saturation divers are sealed into their compression chambers -- which include beds, bathrooms, and hatches through which food and supplies can be delivered -- they're committed to living a life under compression that can last for weeks, even months at a time. It's a bit like space exploration, only mission control isn't back on Earth. They're just on the other side of a wall, but still impossible to access. (The film gives you a great understanding of saturation diving, but for a detailed explanation, you can check out this excellent piece at Atlas Obscura.)
What is Last Breath?
Directed by Alex Parkinson, who co-directed the 2019 documentary of the same name, Last Breath tells the story of Chris Lemons (Cole), a saturation diver who, at work at depths of more than 300 feet below the storm-ravaged North Sea, was left stranded underwater when the umbilical supplying him with light, heat, and breathable gas was accidentally ripped from his suit.
Racing to save their friend, who has just minutes of air left in auxiliary tanks, Lemons' colleagues Duncan Allcock (Harrelson) and David Yuasa (Liu) must go back down to save him in what will likely be the most dangerous dive of their lives.
Last Breath is now in theaters, get tickets at Fandango!
