The Extraordinary Story of the World's Deepest Ever Submarine Rescue

On August 29, 1973, a Canadian deep-sea submersible named Pisces III, piloted by two men, became trapped on the seabed at a depth of nearly 1,600 feet, around 150 miles off the coast of Ireland in the Irish Sea.

The men—former British Royal Navy officer Roger Mallinson and engineer Roger Chapman—were on a routine dive to lay transatlantic telecommunication cable when the mission went badly wrong.

What happened over the course of the next three days captured the world's attention as British, American and Canadian dive teams attempted to save the men from their trapped submersible, which measured just six feet in diameter.

Chapman and Mallinson had to battle against despair and carbon dioxide poisoning as their limited oxygen supply dwindled. In fact, by the time they were rescued—after spending more than 84 hours in the submersible—the pair only had 12 minutes of oxygen left in the tank.

While the incident—considered the deepest submarine rescue in history—made headlines at the time, it has since largely been forgotten about.

To bring the extraordinary tale to life, journalist and producer Stephen McGinty has reconstructed the dramatic events of those three days in a new book The Dive: The Untold Story of the World's Deepest Submarine Rescue, which will be published on June 8. The story of the event is also being developed into a feature film.

Newsweek spoke to McGinty about the 1973 rescue.

What sparked your interest in this topic? Why did you decide to write a book about it?

I first heard about the rescue of Pisces III about fifteen years ago from a ship's captain while on a cruise around the Aeolian Islands, off the coast of Sicily. I filed it away and two years ago decided to dust the idea down and explore if it would work as, what I imagined, could be a 'non-fiction thriller.' What appealed to me was not only the plight of the men at the bottom of the Atlantic Ocean but this international 'Brotherhood of the Sea'—teams from Britain, Canada and America—who all came together to work on the rescue mission.

How did the submersible become trapped?

After surfacing from a routine dive to bury the transatlantic telephone cable, the rear hatch onboard Pisces III was accidentally pulled open and seawater rushed in causing the submersible to immediately sink due to the excess weight. First the sub sank about 160 feet, only to be caught by the tow rope. However, this couldn't withstand the weight and eventually snapped, sending the sub tumbling 1,500 feet to the bottom.

How dire was the situation that Chapman and Mallinson found themselves in at this point?

The way I like to describe it to the uninitiated is: try to imagine you are in a phone box with a friend, the phone box is at the bottom of the Empire State Building, then everything around you floods to ten stories above the top of the Empire State Building, then turn out all the lights and start bleeding oxygen, then you realize that a rescue—if it can even be attempted—is roughly two days away. Their situation was pretty dire. They didn't even have a water supply. They would have to survive on a tin of lemonade, some cold coffee and condensation licked from the walls.

Pisces III rescue
The Pisces III crew after being rescued (left) and the United States Navy CURV-III remotely operated underwater vehicle (right) used during the mission. This image has been colorized by Newsweek. U.S. Navy

Can you give a brief summary of how the rescue operation played out?

Peter Messervy, a former Royal Navy commander, and Al Trice, a Canadian sub designer, pulled together three different teams: a mini-sub from the U.K.; a mini-sub flown over from Canada, and a remote-controlled submarine with a team from San Diego. The idea was always to have a back-up if anything went wrong and, well, everything did go wrong. The plan was relatively simple: a sister sub would go down with a two-man crew and attach a specially designed grapple hook to the sub then lift it to the surface. But they do say: how do you make God laugh? Tell him your plans.

The first sub to go down lost its lift line; the second sub down couldn't find them. On a third trip they finally found Pisces III, but when they attempted to fix the lift line it locked on then fell out. Time was the enemy during the rescue as the men's oxygen supplies were slowly dwindling. With less than 12 hours to go before the—literal—deadline, a fresh team is helicoptered in and winched down onto the rescue ship, Vickers Voyager, during a wild storm. They help to make crucial repairs and pilot the sub that finally gets the first rescue hook onto Pisces III. A second hook is planted by the American team using their remote-controlled sub.

Then came the lift—which was the worst part.

What were some of the main challenges of the rescue operation? How did the rescue team overcome these?

One problem was finding Pisces III. The floating buoy that ran on a rope from the surface down to the sub had been disconnected a few minutes before Pisces III sank, so although they knew roughly where it left the surface they had no idea where it landed on the seabed. So they knew where the haystack was, just not the needle. The Canadian team finally managed to detect them using sonar by getting Roger Chapman to sing in the hope of picking up the high notes.

Another challenge was using the miniature sub's manipulator arm to fix a rescue hook on Pisces III, which was a bit like threading a needle while wearing a suit of armor.

What was the state of the crew members when they were rescued?

They were suffering from dehydration and Roger Mallinson had mild hypothermia but, over all, they were in remarkable shape given what they had been through. The doctor who examined them commented: "incredible." Emotionally they were hugely relieved and quite shattered. The final lift—which took over two hours—and involved multiple stops and starts and violent swinging was, they both believed, the worst part of the entire ordeal.

Did anything interesting happen in the aftermath of the incident?

The most interesting point was that Roger Chapman set up his own company specializing in rescuing stricken submarines. His team were onsite during the Kursk disaster, but not permitted to access the scene until it was too late but later he and the team were involved in the successful rescue of the crew of the Russian submarine AS-28, which sank in waters off the Kamchatka Peninsula in August 2005.

The pair also formed a life-long bond. Each year on the anniversary Roger Mallinson would call Roger Chapman at the exact moment they reached the surface.