BOSTON - The families of the five people who died on the Titanic tourist submersible are mourning their loss.
All five people aboard a submersible that went missing near the wreck of the Titanic died -- likely in an instant -- when their vessel suffered what the US Coast Guard said was a "catastrophic implosion" in the ocean depths.
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.
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Harding was a billionaire and keen explorer with three Guinness Records to his name, while the Dawoods belonged to one of Pakistan's richest families. Nargeolet was nicknamed "Mr Titanic" for his frequent dives at the site.
Harding's family paid tribute to the aviation tycoon in a statement, saying he was a "passionate explorer" as well as a "loving husband and a dedicated father to his two sons."
"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," the family said.
READ: All five on Titanic sub dead after 'catastrophic' implosion
The Dawoods' loved ones also expressed their "profound grief" at their loss in a brief statement.
"We are truly grateful to all those involved in the rescue operations. Their untiring efforts were a source of strength for us during this time," read the statement.
The British and Pakistani governments expressed their "deepest condolences" to all the men's families.
The US Coast Guard's Rear Admiral John Mauger told reporters that analysis showed debris found on the seafloor -- 500m from the bow of the Titanic -- was consistent with an implosion of the sub's pressure chamber.
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"On behalf of the United States Coast Guard and the entire unified command, I offer my deepest condolences to the families," Mauger said.
OceanGate said its "hearts are with these five souls and every member of their families during this tragic time."
"These men were true explorers who shared a distinct spirit of adventure, and a deep passion for exploring and protecting the world's oceans," it said in a statement.
The Titanic International Society said it could be time to replace manned missions to the wreck with autonomous machines.
"It is time to consider seriously whether human trips to Titanic's wreck should end in the name of safety, with relatively little remaining to be learned from or about the wreck," it said in a Facebook post.
"Crewed submersibles' roles in surveying the wreck now can be assigned to autonomous underwater vehicles."