A debris field from the submersible Titan was found at the bottom of the North Atlantic on Thursday by a robotic diving vehicle deployed from a Canadian search vessel, ending an intense five-day international rescue effort.
Fragments of Titan, which lost contact with its surface support ship about one hour and 45 minutes into a two-hour descent on Sunday, were discovered on the seabed about 488 metres from the bow of the Titanic wreck, about four kilometres below the surface, US coast guard Rear Admiral John Mauger said.
He told reporters on Thursday the debris was consistent with “a catastrophic implosion of the vehicle”, meaning the 6.7m long vessel ultimately collapsed and was crushed under the immense hydrostatic pressure at that depth.
The five who died included Stockton Rush, founder and CEO of OceanGate Expeditions, which operated the submersible and charged $US250,000 ($A374,000) per person for the Titanic trip.
He was piloting the craft.
The others were British billionaire and explorer Hamish Harding, 58; Pakistani-born businessman Shahzada Dawood, 48, and his 19-year-old son, Suleman, both British citizens; and French oceanographer Paul-Henri Nargeolet, 77.
In a statement on Friday, Canada’s Transportation Safety Board (TSB) said it was launching a “safety investigation regarding the circumstances” of Titan’s operation because its surface support vessel, the Polar Prince, was a Canadian-flagged ship.
A TSB team was dispatched to St John’s, Newfoundland, about 643km north of the accident site, to gather information and conduct interviews, the agency said.
Guillermo Sohnlein, who co-founded OceanGate with Rush in 2009, said Rush was “keenly aware” of the dangers of exploring the ocean depths.
“Stockton was one of the most astute risk managers I’d ever met,” said Sohnlein, who left the company in 2013, retaining a minority stake.
“He was very risk-averse.”
Others in the close-knit community of submersible operators and experts noted Stockton and his company opted to forgo certification of Titan’s novel design from industry third parties such as the American Bureau of Shipping.
Some have questioned Stockton’s choice of carbon fibre to fabricate the critical pressure hull of his craft.
“OceanGate had created its own experimental vehicle with materials avoided by others, decided to bypass the certification process designed to assure safety, and chose to ignore the warnings from many experts within the submersible community,” investment manager Ray Dalio, co-founder of the OceanX sea exploration initiative, said in a LinkedIn post on Friday.
British Titanic explorer Dik Barton also pointed to issues raised about the design and maintenance of Titan.
“There were many red flags flying here,” he said.
One would-be Titan passenger, Las Vegas-based investor Jay Bloom, told Reuters he declined a last-minute chance to join the ill-fated Titan excursion with his son out of safety concerns.
Bloom said he was particularly worried about Stockton’s use of consumer-grade parts on Titan, including a video game joystick to control the vessel.
Questions about Titan’s safety surfaced in 2018 during a symposium of industry experts and in a lawsuit by OceanGate’s former head of marine operations, which was settled later that year.
The disaster marks the first known fatalities in more than 60 years of civilian deep-sea exploration.Â
But OceanGate was free to go its own way because international waters are beyond government regulation, industry experts say.
The company has not addressed queries about its lack of industry certification or other safety issues.