The Transportation Safety Board of Canada (TSB) has said it is launching a safety investigation into the implosion of the Titan submersible in the North Atlantic in which five people died.
In a short statement, it said: "In accordance with the Canadian Transportation Accident Investigation and Safety Board Act and international agreements, the TSB, as the investigation authority of the flag state of the support vessel involved in the occurrence, will conduct a safety investigation regarding the circumstances of this operation conducted by the Canadian-flagged vessel Polar Prince.
"A team of TSB investigators is travelling to St John's, Newfoundland and Labrador [in Canada], to gather information, conduct interviews, and assess the occurrence.
"In the coming days, we will coordinate our activities with other agencies involved."
Relatives and colleagues are mourning the five people who died when their sub imploded during a deep dive to the Titanic wreck, prompting questions about safety rules for such adventures into the ocean depths.
Debris from Titan, which had been missing since Sunday, was detected yesterday by a robotic diving vehicle deployed from a Canadian ship as part of an international rescue effort.
Remains of the submersible, which lost contact with a surface ship about 1 hour and 45 minutes into a 2-hour descent, were discovered on the seabed about 488m from the bow of the Titanic wreck, around 4km below the surface, US Coast Guard Rear Admiral John Mauger said.
He told reporters yesterday the debris was consistent with "a catastrophic implosion of the vehicle."
The five who died included Stockton Rush, US founder and chief executive officer of OceanGate Expeditions, which operated the submersible and charged $250,000 (€292,000) per person to make 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.
"These men were true explorers who shared a distinct spirit of adventure, and a deep passion for exploring and protecting the world's oceans," OceanGate said.
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Guillermo Söhnlein, who co-founded OceanGate with Mr Rush in 2009, said Mr 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 Mr Söhnlein, who left the company in 2013, retaining a minority stake. "He was very risk-averse."
British Titanic explorer Dik Barton paid tribute to the work of his friend Mr Nargeolet but noted issues raised with the design and maintenance of the craft.
"Everyone's wise after the event, but as we're hearing before, unfortunately there were many red flags flying here," he said.
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.
Worldwide media coverage of the search overshadowed the aftermath of a far greater disaster from the wreck of a migrant vessel off Greece last week that killed hundreds of people.
Teams from the US, Canada, France and Britain had spent days scanning a vast expanse of open sea for the Titan.
The US Coast Guard's Mauger said it was too early to say when the Titan met its fate.
The position of debris relatively close to the wreck suggested it happened near the end of Sunday's descent.
The US Navy monitors that part of the Atlantic for submarine activity and said an analysis of acoustic data detected "an anomaly consistent with an implosion or explosion" near the submersible's location when communication with Titan was lost.
The acoustic data was shared immediately with the unified command led by the US Coast Guard, according to Navy officials, who spoke on condition of anonymity. It was decided that the acoustic data was not definitive and the search and rescue mission should continue.
One Navy official said that while it was not immediately clear what the cost to the Navy would be of the rescue effort, it was likely to be negligible.
Filmmaker James Cameron, who directed the 1997 Oscar-winning film "Titanic" that did much to revive global interest in the ocean liner that sank in 1912, said he learned of the acoustic findings within a day of the submersible disappearing and knew what it meant.
"I sent emails to everybody I know and said we've lost some friends. The sub had imploded," Mr Cameron, who has ventured to the wreck in submersibles, said.
Scientist and journalist Michael Guillen, who survived an expedition in 2000 that became trapped in the wreck's propeller, said: "We need to stop, pause and ask this question, 'why do you want to go to the Titanic and how do you get there safely?'"
The Titanic sank after hitting an iceberg on its first voyage, killing more than 1,500 people aboard.
It lies about 1,450km east of Cape Cod, Massachusetts and 640km south of St John's, Newfoundland.
Additional reporting Reuters
