James Cameron reveals similarities between Titanic disaster and submersible tragedy

Director James Cameron reacted to news the five people aboard the Titan submersible had died in what appeared to have been a "catastrophic implosion", according to the US Coast Guard.

It followed a multi-day international search for the vessel that was en route to visit the Titanic wreck on the floor of the Atlantic Ocean.

Mr Cameron told the US' ABC News that members of the deep submergence engineering community had written to the company behind the dive with concerns it was "too experimental to carry passengers".

"I'm struck by the similarity of the Titanic disaster itself, where the captain was repeatedly warned about ice ahead of his ship and yet steamed at full speed into an ice field on a moonless night and many people died as a result.

"For a very similar tragedy where warnings went unheeded to take place at the same exact site... it's just astonishing; it's quite surreal. "

The filmmaker has dived to the Titanic wreck more than 30 times amongst a total of 72 deep submersible dives, according to Deep Sea Challenge.

He said the wreck was a "twisted mess" and submersibles risked becoming caught.

"Entanglement was always a concern of ours but we dove a two-sub system.

"We always felt confident that if one of the subs got ensnared, you'd still have communication, you'd still have life support, you still have power and another sub there to help manage the problem.

"This sub [Titan] had no backup.

"This OceanGate sub had sensors on the inside of the hull to give them warning when it was starting to crack and I think if that's your idea of safety then you're doing it wrong."

Early on June 23 Sydney time OceanGate Expeditions, the US-based company that operated the Titan confirmed the deaths of the five crewmembers.

The five people aboard included the British billionaire and explorer Hamish Harding, 58; Pakistani-born business magnate Shahzada Dawood, 48, and his 19-year-old son, Suleman, both British citizens; French oceanographer and Titanic expert Paul-Henri Nargeolet, 77, who had visited the wreck dozens of times; and Stockton Rush, the US founder and chief executive of OceanGate, who was piloting the submersible.

"These men were true explorers who shared a distinct spirit of adventure, and a deep passion for exploring and protecting the world's oceans," the company said in a statement.

"Our hearts are with these five souls and every member of their families during this tragic time."

An unmanned deep-sea robot deployed from a Canadian ship discovered the wreckage of the Titan on Thursday morning in the US.

It was about 488 metres from the bow of the century-old wreck and 4km below the surface, US coast guard Rear Admiral John Mauger said at a press conference.

"The debris field here is consistent with a catastrophic implosion of the vehicle," Mauger said.

Rescue teams from several countries had spent days searching thousands of square miles of open seas with planes and ships for any sign of the 6.7-metre Titan.

The submersible lost contact on Sunday morning with its support ship about an hour and 45 minutes into what should have been a two-hour descent.

Mauger said it was too early to tell whether the vessel's failure occurred then or at a later time.

The detection of undersea noises on Tuesday and Wednesday using sonar buoys dropped from Canadian aircraft had temporarily offered hope that the people on board the submersible were alive and trying to communicate by banging on the hull.

But officials had warned that analysis of the sound was inconclusive and that the noises might not have emanated from the Titan at all.

"There doesn't appear to be any relation between the noises and the location of the debris field on the sea floor," Mauger said on Thursday.

The search had grown increasingly desperate on Thursday, when the estimated 96-hour air supply was expected to run out if the Titan were still intact.

The Titanic, which sank in 1912 on its maiden voyage after hitting an iceberg, killing more than 1500 people, lies about 1450km east of Cape Cod, Massachusetts, and 640km south of St John's, Newfoundland.

The expedition to the wreck, which OceanGate has been operating since 2021, cost $US250,000 ($A368,000) per person, according to OceanGate's website.

Questions about Titan's safety were raised in 2018 during a symposium of submersible industry experts and in a lawsuit by OceanGate's former head of marine operations, which was settled later that year.

On Thursday, the deployment of two specialised deep-sea unmanned vehicles expanded the effort to the ocean's depths, where immense pressure and pitch-black darkness had promised to complicate any rescue mission.

With Australian Associated Press