The families of the victims involved in the Titan submersible tragedy have paid emotional tributes to the deceased.
The British billionaire adventurer Hamish Harding was described as "a guide, an inspiration, a support, and a living legend" following the news of his death on Thursday.
The U.S. Coast Guard confirmed the tail cone of the deep-sea vessel was discovered around 500 meters (1640 feet) from the bow of the Titanic wreckage during a press conference in Boston.
Rear Adm. John Mauger said further debris was also found, in the North Atlantic Ocean off the coast of Newfoundland, that was "consistent with a catastrophic loss of the pressure chamber."
OceanGate Expeditions said its pilot and chief executive Stockton Rush – along with Harding and fellow U.K. citizens Shahzada Dawood and his 19-year-old son Suleman Dawood, and French national Paul-Henri Nargeolet, "have sadly been lost."
In a short statement, Harding's family said: "He was one of a kind and we adored him.
"He was a passionate explorer – whatever the terrain – who lived his life for his family, his business and for the next adventure.
"What he achieved in his lifetime was truly remarkable and if we can take any small consolation from this tragedy, it's that we lost him doing what he loved."
Harding's family said his death has left a "gap in our lives that can never be filled," and that they were "united in grief" with the families of the others who had died.
"We know that Hamish would have been immensely proud to see how nations, experts, industry colleagues and friends came together for the search and we extend our heartfelt thanks for all their efforts," they said.
Shahzada Dawood's company paid tribute to him and his son after their deaths.
In a statement, Engro Corporation, the Pakistani conglomerate that Dawood was vice chairman of, said: "With heavy hearts and great sadness, we grieve the loss of our vice chairman, Shahzada Dawood, and his beloved son, Suleman Dawood.
"Our thoughts and prayers are with the Dawood family at this tragic time.
"We extend our heartfelt condolences to the family, colleagues, friends and all those around the world who grieve this unthinkable loss."
Rear Admiral Mauger said there did not appear to be any connection between the underwater noises detected during the search and rescue mission and the location of the debris on the seafloor.
"This was a catastrophic implosion of the vessel which would have generated a significant broadband sound down there that the sonar buoys would have picked up," he said.
Undersea expert Paul Hankin said five major pieces of debris helped to identify it as from the Titan submersible – including the vessel's nose cone and the front end bell of the pressure hull.
According to court documents, safety concerns had previously been raised about the Titan submersible by a former employee of OceanGate.
The filings said David Lochridge, OceanGate's former director of marine operations, claimed wrongful dismissal after flagging worries about the company's alleged "refusal to conduct critical, non-destructive testing of the experimental design."
Court papers suggest Lochridge "identified numerous issues that posed serious safety concerns" but he was allegedly "met with hostility and denial of access" to necessary documents before later being fired.
Foreign Secretary James Cleverly described the update as "tragic news" and said the U.K. Government is closely supporting the British families affected.
The White House said the families of those who died had "been through a harrowing ordeal over the past few days, and we are keeping them in our thoughts and prayers."
