Warning: SPOILERS ahead for Last Breath.Alex Parkinson’s debut film Last Breath is a dramatic rendering of an extraordinary true story with a remarkable ending. The movie demonstrates just how much the human body can withstand, even in the depths of a stormy sea without any access to oxygen. It shows saturation diver Chris Lemons, left for ᴅᴇᴀᴅ at the bottom of the North Sea off the coast of Scotland, somehow being revived a half-hour after his emergency oxygen canister was emptied and he gradually slipped into unconsciousness. His colleagues and an entire support crew were responsible for rescuing him but didn’t think they’d find him alive.

Lemons and his two colleagues, Duncan Allcock and Dave Yuasa, were diving to the bottom of the sea to conduct pressure testing for an oil drilling template. During their dive, their support boat’s system went down, leaving it prone to sea tides. As the boat began to drift, it stretched the umbilical cords supplying the two divers in the water below, Lemons and Yuasa, with heat and oxygen to breaking point. Lemons’ umbilical cord snapped, leaving him breathless and lost at sea. He was finally picked up by Yuasa, 40 minutes later, once the support boat had stabilized.

How Diver Chris Lemons Survived Without Oxygen In Last Breath

His Remarkable Story Has Confounded Scientists

Incredibly, when Yuasa carried Lemons up to the diving bell, where Allcock was waiting, Lemons was still alive. The human body can typically continue functioning without oxygen for four to five minutes, at a normal rate of breathing (via Medline Plus). Chris Lemons was stranded for around 40 minutes, supposedly with just five minutes of oxygen in his emergency tank. It’s thought that he spent a total of 29 minutes without access to any oxygen intake at all.

Even 330 feet underwater, where high water pressure causes tissue compression to concentrate oxygen in the body — and having just been breathing an especially concentrated form of helium and oxygen via his umbilical cord — Lemons should have lasted a maximum of nine to 10 minutes before his organs gave in. Yet, somehow, he came out of the ordeal unscathed. As the postscript of Last Breath reports, his survival against all odds continues to perplex scientists to this day.

Last Breath shows Lemons gradually losing consciousness as his body fights to conserve what little oxygen is left in his bloodstream. Yuasa then reaches him just over half an hour after they initially lost contact on the seabed, and drags him up to the diving bell, where Allcock performs the kiss of life. After two CPR sessions, Lemons chokes, and his breathing returns to normal. This is almost exactly what happened in the true story behind Last Breath, and Lemons suffered no lasting effects from his near-death experience.

Those who watch Last Breath through to the end will see the speculation that Lemons’ low body temperature combined with high water pressure to slow his metabolic rate to an abnormal degree. This unique situation mᴀssively extended his body’s capacity to function without taking in more oxygen, far beyond the maximum timeframe within which human survival should be possible.

Why Lemons Was Left Without Oxygen During His Dive

The Cord Carrying Oxygen To Him From His Diving Boat Snapped

Lemons wound up in this situation in the first place due to an especially unfortunate set of circumstances. The catastrophic failure of the dynamic positioning system on his support boat, the Bibby Topaz, was a highly unlikely event in itself, because the system had several different forms of backup for precisely this kind of problem. Yet all the backups also went down at the same time, rendering the boat incapable of holding its position in the water. What’s more, this dynamic positioning failure led to both Yuasa and Lemons being dragged away from the underwater site where they were situated.

Despite this, Yuasa managed to make it back to the diving bell fairly easily. Lemons suffered further misfortune when his umbilical cord became jammed under a metal part sticking out of the drilling template on the seabed. When the boat moved far enough away from the template, his cord snapped, cutting off his supply of oxygen from the boat. Lemons switched on the emergency oxygen canisters he had strapped to his back, but after five minutes, they were empty, and he was unable to breathe.

What Caused The Diver Support Boat Bibby Topaz To Lose Dynamic Positioning

A Catastrophic System Failure That’s Difficult To Explain

The Bibby Topaz losing the dynamic positioning technology it needed to situate itself in the right spot to support its divers was the first cause of the events which almost led to Lemons’ tragic death. Dynamic positioning is an automated form of GPS technology which operates via a boat’s onboard computer system (via The Nautical Insтιтute). It effectively allows a boat to anchor itself in a single position regardless of sea tides or currents, without the need to actually drop anchor, which would be impractical at a depth of over 300 feet.

It’s never made clear in Last Breath what exactly causes the system failure that leads the Bibby Topaz to lose its dynamic positioning, nor was it clear to the boat’s crew in real life. The computer system simply malfunctioned, and needed to be reset. In the movie, the crew’s dynamic positioning operator, played by Josef Altin, is then shown rewiring the computer system to initiate the reset manually. Luckily, he manages it just in time to get Yuasa back in the water to save Lemons.

How Lemons’ Colleagues And The Bibby Topaz Crew Managed To Rescue Him

They Managed To Pull Him Up To The Diving Bell Once The Boat Regained Positioning

After attempting to pick an unconscious Lemons up from his position at the bottom of the sea with a remotely operated vehicle, the crew of the Bibby Topaz sends his fellow diver, Dave Yuasa, back down to rescue him. This moment serves as the climactic scene of Woody Harrelson’s thriller, with Yuasa using Lemons’ broken umbilical as a rope to pull them both back up to the diving bell, pulling a cumulative weight of more than 300 kilos.

Allcock then performs CPR on his colleague, who soon breathes his first breath in more than 25 minutes. Still, Yuasa and Allcock face a nervous wait before Lemons finally regains consciousness, completing this incredible rescue story.

How Last Breath’s Ending Compares To The True Story

The True Story Of Lemons’ First Breath Is Even More Unbelievable

In the true story of Last Breath, what happened when Lemons returned to the cabin of the diving bell was even more unbelievable than the suspenseful dramatization in the movie. Parkinson made a 2019 documentary about the story before this dramatization, during which Allcock explains that Lemons regained consciousness almost as soon as he choked his first breath following the CPR. Extraordinarily, he then climbed up the ladder into the cabin himself.

Lemons was talking normally within moments of having been out cold and presumed ᴅᴇᴀᴅ, and he even wanted to take his diving suit off. This minor difference between the 2025 version of Last Breath and reality is just about the only dramatic embellishment at the end of the movie. Just like his on-screen counterpart, the real Chris Lemons was reported to be in good health in the hours following his accident. The only discernible difference to his life after the diving accident was that he now had a famous miracle of human resilience to his name.

Sources: Medline Plus, The Nautical Insтιтute