Three other subs visiting Titanic almost suffered the same fate as Titan

The loss of the submersible Titan during its expedition to the Titanic has raised questions about the vessel's safety, but Titan is only the latest sub to find itself in peril at the site of the world's most famous shipwreck.

Of the 10 submarines in the world that can reach depths of 4,000 metres or greater, the Titan, owned by exploration company OceanGate Expeditions, was the only one that wasn't certified by any regulatory body, and OceanGate had been warned by both industry experts and one of its own senior employees that the sub might be unsafe.

Still, no matter how reliable the vehicle, diving to such extreme ocean depths is always risky. At least three previous expeditions to the Titanic had close calls that could have cost the crews their lives.

An IMAX shoot hits a snag

An adviser to the team that rediscovered Titanic in 1985, Canadian undersea physician Dr. Joe MacInnis had already participated in several dives to the site by the time he co-led a joint Canadian-Russian-American expedition there in 1991.

In addition to undertaking biological and geological studies of the sunken ship, the group planned to capture the wreckage on IMAX film – their footage became the basis for the 1995 documentary Titanica.

Two Russian Mir submersibles made 17 dives over the course of the expedition, and on the last one they hit a literal snag.

MacInnis's sub had set down in the wheelhouse, at the very spot where Captain Edward Smith may have stood when Titanic sank beneath the waves. When the crew finished filming and tried to lift off the platform, they realized they were caught on something.

After a moment of panic and a string of expletives, they called in the second Mir sub for assistance.

The pilot of that second vessel was able to see that their left landing skid had slipped under a mass of wires, possibly phone cables that had once led into the wheelhouse, and give them directions on how to manoeuvre their way out of the tangle.

"We had that second pilot, that second sub, self-rescue capability," said MacInnis in an interview with Times Radio, "so we were very fortunate."

Powerless at the bottom of the sea

Another film shoot at the shipwreck led to a near-death experience for director James Cameron.

Cameron made several trips down to the wreckage in fall 1995 while filming for his 1997 blockbuster Titanic, and he was on his third dive with sub pilot Dr. Anatoly Sagalevich and a Russian engineer when they encountered an unexpected sandstorm on the ocean floor.

As Cameron recalls in his 2009 biography The Futurist by author Rebecca Keegan: "Anatoly said 'Oh, no,' something you never want to hear a pilot say, and we locked eyes for a second."

Fighting against the strong currents had sapped the sub's power supply, and they were almost out of batteries.

Immediately, they aborted the dive, but, at 80 feet above the seabed, it was as though they had hit a ceiling. The sub stopped rising and sank back to the ocean floor.

They sat for a half hour in total darkness and near-freezing temperatures to give their battery a rest before trying again, only to be stopped for a second time at 80 feet.

Unbeknownst to them, they were caught in a downdraft caused by the flow of the current over the shipwreck. In a stroke of good luck, however, each time the stream pushed them back down it also blew them a bit further away from Titanic.

On their third attempt, they held their breath when they hit 80 feet but continued to rise, breaking the surface five hours later.

Treacherous currents

Despite his fear of water, Michael Guillen couldn't pass up the opportunity to be the first reporter in 88 years to visit the Titanic when he was invited to dive there in 2000.

Sub pilot Viktor Nischeta took Guillen and his dive partner on a one-hour tour of the wreckage, but, as the sub crossed the debris field between the ship's front section and the stern, Guillen realized they were speeding up. Like Cameron's crew, they were caught in one of the deep sea's unpredictable currents.

"A split-second later, [our sub] slammed into the Titanic's propeller," Guillen recounts in his book Believing is Seeing. "I felt the shock of the collision; shards of reddish, rusty debris showered down on our submersible, obscuring my view through the porthole."

The little sub was jammed tight in the gigantic propeller's housing. As Nischeta rocked the vessel back and forth like a car bogged down in mud, Guillen thought to himself: "This is how it's going to end for you."

After almost an hour in tense silence, there was a sudden change in the way Mir felt under their feet. The growling of the engine ceased, and the sub felt weightless again.

"OK?" Guillen asked tentatively.

Nischeta grinned. "No problem!"

Like being in a dishwasher

In 2005, French deep-sea explorer Paul-Henri Nargeolet, one of the five men who died on Titan, wrote in an open letter to Titanic shipwreck discoverer Bob Ballard:

"From my 11-year experience diving on Titanic, I can assure you that the ocean floor around that wreck is not a quiet place. Often it is more like a dishwasher."

Between erratic currents, a total lack of warmth and daylight, and the rusting hulk of the ship itself, whose ruptured hull and snapped cables reach out into the darkness to snare passing watercraft, diving to the Titanic is always a dangerous proposition.

In the months to come, there will no doubt be an investigation into what went wrong on Titan, but, though we can mitigate the risks, it will never be completely safe in our lifetimes to visit the deep ocean – one of the few places on earth utterly inhospitable to human life.

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