Missing Titanic submersible live updates: Texts show OceanGate CEO dismissed concerns

Explorer Robert Ballard, who was on the 1985 expedition that discovered the Titanic wreckage and has made many dives since, reacted to news of the implosion with ABC News on Thursday.

"It's very tragic what happened, I know the people that passed away," he said, adding that he's known OceanGate CEO Stockton Rush, who was piloting the vessel, for 20 years. "I know this was his dream, so my heart goes out to him and his family and the families of all the people who lost loved ones."

Ballard surmised the crew likely experienced difficulties and began to drop weights to ascend to the surface but "never made it."

"If you're on your way up and you're buoyant and you don't make it, it's a catastrophic implosion," he said.

"I don't think people can appreciate the amazing energy involved in the destructive process of an implosion," Ballard continued. "It just takes and literally shreds everything. So it's extremely powerful."

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Bob Ballard reacts to 'catastrophic implosion' of Titanic submersible

Five people, including the CEO of OceanGate, were aboard the sub when it imploded.

ABCNews.com

The Explorers Club reacted to news of the submersible's implosion, saying in a letter to members on Thursday: "Our hearts are broken."

President Richard Garriott de Cayeux noted that two of the passengers lost in the implosion -- Hamish Harding and Paul-Henri Nargeolet -- were members of the Explorers Club, while OceanGate CEO Stockton Rush was a friend of the society who had conducted lectures at its headquarters.

"Hamish Harding is a dear friend to me personally and to The Explorers Club," Garriott de Cayeux said. "He holds several world records and has continued to push dragons off maps both in person and through supporting expeditions and worthy causes."

Nargeolet was "one of the foremost experts on submersible expeditions to the Titanic," Garriott de Cayeux said.

"They were both drawn to explore, like so many of us, and did so in the name of meaningful science for the betterment of mankind," he continued. "They pushed themselves in their entrepreneurial pursuits as they did in exploration."

In reacting to news of the OceanGate submersible implosion, "Titanic" director James Cameron told ABC News that he was "struck by the similarity of the Titanic disaster itself, where the captain was repeatedly warned about ice ahead of his ship and yet he steamed at full speed into an ice field."

Cameron, who has built his own submersible, was critical of OceanGate's use of a carbon-fiber hull, calling it "fundamentally flawed."

OceanGate CEO Stockton Rush, who was among the five passengers killed on the submersible, had previously said he believed a sub made with carbon fiber would have a better strength-to-buoyancy ratio than titanium.

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James Cameron on similarities between Titanic wreck and tourist sub

The director of “Titanic” said “many people in the community were very concerned” about the Titan submersible.

ABCNews.com

"Titanic" director James Cameron, who has explored the wreckage site himself, called the implosion "quite surreal" and noted that one of the passengers killed, Paul-Henri Nargeolet, was a friend of his.

"For him to have died tragically in this way is almost impossible for me to process," Cameron told ABC News Thursday.