Take a deep breath. Got it? Good, now see how long you can hold it for - without putting yourself in danger, of course.

This might sound like a strange opening to an article about a Netflix documentary, but viewers have admitted they need all the oxygen they can get while watching one of the new arrivals on the streaming service.

Anastasia Shuraeva/Pexels

The Deepest Breath dropped on Netflix on 19 July, and was quickly picked up by Friday's episode of Celebrity Gogglebox, when the famous faces sat down to watch it.

It tells the story of two free divers, Alessia Zecchini and Stephen Keenan, as they team up to break world records in the sport, while simultaneously trying their best to stay safe.

Zecchini, from Italy, holds records in the sport, and in March set a new world record for free diving with two fins in constant buoyancy by descending to a depth of 109 meters in the waters of Moalboal, Philippines.

Keenan, from Ireland, has opened a free diving school and has acted as a safety diver on countless dives.

Without any scuba gear to help them, free divers hold their breath while attempting to dive to extreme depths. They're assisted by safety divers, who can help them with their ascent to the surface if they run out of oxygen - which is exactly what Keenan does for Zecchini in The Deepest Breath.

Netflix

The doc sees Zecchini prepare to take on the legendary Blue Hole in Dahab, Egypt, where she must dive 184 feet below the Red Sea and take on an 85-foot-long tunnel.

Viewers see Zecchini prepare for the dive with long breaths on the surface, but it's the moments when she's without oxygen that have left people gasping for air.

After watching the film, one viewer wrote: "Watching The Deepest Breath and wow. And I can't breathe."

Another commented: "If you need something to watch on Netflix, check out The Deepest Breath. It is fascinating, stressful, and beautiful. I felt like I couldn’t breathe at times just watching it."

A third added: "The Deepest Breath on Netflix is one of the best documentaries I’ve ever seen."

Twitter/@ladychippytea

Filmmaker Laura McGann told Netflix's Tudum there was 'something otherworldly' about witnessing the sport, saying: “I could feel that there was just an at-oneness that these people had, that they were so relaxed and they were just meant to be there. It was really gentle — but also powerful and hard to believe.”

She also explained what the divers go through while underwater, saying: “You hear your own heartbeat. Everything slows as you conserve oxygen in your body. We wanted to represent that.”

The Deepest Breath is available to stream now on Netflix.