TRAPPED Titanic sub CEO Stockton Rush admitted his biggest fear was the vessel not being able to get back to the surface.
The 61-year-old is stuck on stricken Titan with four other crew members as robots comb the seabed in the desperate hope of a miracle.
Oxygen likely ran out on the sub at 12.08pm BST (7.08ET) - but rescue crews are continuing their operation.
Former passengers on the "experimental" sub have raised concerns over the apparent lack of safety equipment, and the fact there's no emergency escape.
In a haunting interview last year, Mr Rush told how his main worry was that the sub - created by OceanGate and steered by a gaming controller - would get trapped under the water.
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He told CBS: "What I worry about most are things that will stop me from being able to get to the surface.
"Overhangs, fish nets, entanglement hazards."
But he brushed off the concern, and said the 22ft vessel would be able to avoid such hazards.
Mr Rush, who is stuck on the sub with Hamish Harding, Paul-Henri Nargeolet, Shahzada Dawood and his son Suleman, added: "And, that's just a technique, piloting technique.
"It's pretty clear - if it's an overhang, don't go under it. If there is a net, don't go near it.
"So, you can avoid those if you are just slow and steady."
He also claimed there should be "limits" to safety precautions.
Mr Rush continued: "You know, at some point, safety is just a pure waste.
"I mean, if you just want to be safe, don't get out of bed, don't get in your car, don't do anything. At some point, you're going to take some risk, and it really is a risk-reward question.
"I think I can do this just as safely while breaking the rules."
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And in clip from last year shared on YouTube, Mr Rush can be heard saying he had "broken some of the rules" to make the sub.
He said the windows became "squeezed" because of the water pressure on descent, and a "warning" goes off if the vessel is going to "fail".
Experts fear the sub may well have failed as it made its way down to the Titanic wreckage 12,500ft below on Sunday.
Its final "ping" to mothership Polar Prince placed the sub directly above the ruins.
Josh Gates, who ventured onto OceanGate's sub for a "shakedown dive" in 2021, said he swiftly decided to "back off" from becoming part of the dive team.
Mr Gates told how there were a series of errors with the system during his trip just two years ago.
He told Sky News: "Some of them [the systems] didn't perform well at all.
"We had issues with thrusters, we had issues with computer control aboard.
"There was so little data available about managing that risk and what it looked like if this sub went up and down as many times as it was going to."
He said following the test dive, he "ultimately decided to back off" from the dive project team as he "couldn't get comfortable with the design of Titan".
Mr Gates added: "An innovative novel design comes with a lot of mysteries as to how it's going to perform over time."
Chilling footage reveals the claustrophobic conditions inside the sub built from "improvised" stock including camping lights.
Concerns have been raised over the "experimental" nature of the vessel and the inability for the passengers inside to escape since they are bolted within.
Made by OceanGate Expeditions, the cramped 22ft (6.7m) carbon fibre submersible has only one porthole at the front and does not have a GPS system.
The deep-sea sub is instead guided by text messages exchanged using an acoustic system with a team waiting helplessly above water.
OceanGate claimed Boeing and the University of Washington were involved in the design, but both have denied this.
Arthur Loibl, who embarked on the daring voyage in 2021 with Titanic expert Paul-Henri Nargeolet and Mr Rush, branded the trip a "suicide mission".
But just before it was set to launch, he told how the bracket of the stabilisation tube - designed to balance the sub - tore and it was reattached with zip ties.
Journalist David Pogue travelled onboard the Titan last year and shared his concerns over some components of the sub seemed that "off-the shelf, sort of improvised".
He told the BBC: "You steer this sub with an Xbox game controller [and] some of the ballast is [built from] abandoned construction pipes."
And the inside lighting was bought from a camping shop.
He also explained that there is "no way" to communicate with the mini-van size vessel, nor can anyone inside the sub escape without external help.
Passengers are sealed within the main cabin by hefty bolts secured from the outside and have to be removed using external crew.
"There's no backup, there's no escape pod," he said. "It's get to the surface or die."
He also revealed the sub vanished for hours on another expedition last year.
Bosses of the sub were even previously embroiled in a lawsuit over the vessel’s potentially dangerous flaws after a safety manager spoke out about his concerns.
Tourists fork out almost £200,000 to take part in the expedition - but must sign a contract before boarding.
Passengers are made to acknowledge that the submarine is “an experimental vessel”.
The chilling contract also states that their trip “could result in physical injury, disability, emotional trauma or death”.
