Oceangate's Titan debris was identified by the US Coast Guard USCG on Thursday near the Titanic ship wreckage near the ocean floor,  and all five of the passengers on board the submersible are presumed dead.

It is believed that Titan suffered a "catastrophic loss of pressure" which led to its implosion and the submarine's remains will probably never be recovered, former navy surgeon Dr. Dale Molé was cited by media outlets as saying.

The implosion would have caused extreme damage to the passenger's bodies, he added, noting that they likely suffered instantaneous death.

"Much like an airplane flying into the side of a mountain at high speed, I doubt there are any human remains left to be recovered," he said.

"Basically, alive one second and dead the next."

“The pressure outside the hull would have been about 6,000 pounds per square inch whereas the pressure inside the passenger compartment was normal atmospheric pressure or about 14.7 pounds per square inch. So when the hull imploded it did so instantaneously and with massive force. It was essentially like an explosion, but the shock wave was directed inward instead of outward,” the navy captain continued.

OceanGate’s submarine was lost last Sunday during an expedition to the Titanic wreckage, located about 900 miles east of Cape Cod in the North Atlantic and at a depth of approximately 13,000 feet.

The undersea expeditions began transporting small crews of "citizen scientists" in a five-person mini-sub for $125,000 per person two years ago. Titan's voyage takes tourists near the wreckage of the Titanic for exploring the remains of the historic ship and its surrounding ecosystem.

But just under two hours after it took it started its descent, contact was lost with the submarine and a search-and-rescue mission was launched.

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US Rear Admiral John Mauger told reporters in Boston on Friday that analysis showed debris found on the seafloor, 1,600 feet (500 meters) from the bow of the Titanic, was consistent with the implosion of the sub's pressure chamber.

"On behalf of the United States Coast Guard and the entire unified command, I offer my deepest condolences to the families," Mauger said.

On board were British explorer Hamish Harding, French submarine expert Paul-Henri Nargeolet, Pakistani-British tycoon Shahzada Dawood and his son Suleman, and Stockton Rush, CEO of the sub's operator OceanGate Expeditions.

Rush founded the naval tourism company in 2009 and had been since developing a submersible capable of diving 20,000 feet below the water's surface.

"These men were true explorers who shared a distinct spirit of adventure, and a deep passion for exploring and protecting the world's oceans. Our hearts are with these five souls and every member of their families during this tragic time," OceanGate said in a statement.

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