How ‘Titan’ Passengers' Family & Friends Are Facing Tragedy: 'My Heart Dropped' (Exclusive)

“This was a catastrophe that should never have happened, period," retired U.S. Navy Captain Alfred Scott McLaren tells PEOPLE

In the aftermath of the fatal Titan implosion, family and friends of those aboard the submersible have been speaking out.

Five people were aboard the Titan when it disappeared and imploded on Father's Day: OceanGate CEO Stockton Rush, 61, British Pakistani billionaire Shahzada Dawood, 48, and his son Suleman Dawood, 19, British billionaire Hamish Harding, 58, and Titanic expert Paul-Henri Nargeolet, 77.

Nargeolet ventured to the Titanic wreckage more than 35 times, becoming known as “Mr. Titanic.” The ocean was his “home away from home,” said stepson John Paschall.

Explorer Fred Hagen, who previously worked as a mission specialist on the Titan, originally feared that the victims were stuck deep in the Atlantic, where it can get “extremely cold.”

Related: 111 Years of Tragedy: How 'Titanic' Obsession Led to 'Titan' Nightmare — and What's Next for Wreck

Hagen tells PEOPLE he's had “recurring nightmarish” thoughts about how he could have helped his friend from possibly freezing — even though experts ultimately determined that the submersible likely imploded instantaneously.

The Pennsylvania man had hoped to gift his friend a pair of leather Uggs similar to the ones he wore during his first trip to the Titanic, but said he “never got around to it.”

“He's suffering, he may be dying, and his feet are probably frozen,” he recalls thinking. “And if I had just ... made the effort to get to send those Uggs to him like I intended then he wouldn't have had to die with frozen feet.”

Retired U.S. Navy Captain Alfred Scott McLaren also had high praise for Nargeolet, whom he describes as a “true explorer” in life. Nargeolet’s death, McLaren adds, is a “tremendous loss” within the underwater community.

In November 2022, the Titan was the subject of a segment from CBS Sunday Morning correspondent David Pogue. Speaking with PEOPLE, the journalist recalls how he ventured down to the Titanic wreckage on the Titan in July 2022.

During the dive, Nargeolet shared a quote that “stuck with him” beyond the interview, Pogue recalls: “Every submersible is a prototype."

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“There's only one [Titan submersible]. There's not a spare,” Pogue tells PEOPLE. “There wasn't a 1.0 version and this is the 2.0. It is one of a kind, made of a lot of custom parts, and that's why they're all called experimental. They're not iPhones produced by the millions."

“And that's why this submersible, and all of the submersibles, have constant mechanical problems,” he adds. “Little things go wrong all the time.”

A lifelong Titanic fan, businessman Shahzada was thrilled about the trip, and was to take his wife, Christine, she told the BBC.

But their son Suleman — a student at the University of Strathclyde in Glasgow, Scotland— “really wanted to go,” Christine told the outlet, and took a Rubik’s Cube with him to solve at the Titanic.

“I lost hope when we passed the 96 hours mark,” Christine said.

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As for the final moments and words she shared with her husband and son, Christine said, “Well we just hugged and joked actually, because Shahzada was so excited to go down, he was like a little child. So the sentence, 'We lost comm,' I think that will be a sentence I never want to hear in my life again.”

The family — including daughter Alina, 17 — are “profoundly grateful to those from all over the world who have stood by us," they said in a statement.

Harding was a well-known adventurer, though his specialty was flying. The British pilot started his own aviation company, had also been to space with Amazon billionaire Jeff Bezos in 2022 and had visited to the South Pole twice.

Tracy Ryan — who is friends with Linda Harding, wife of the late renowned explorer Hamish — tells PEOPLE that Linda became “very, very overwhelmed" upon learning that her husband was among those missing.

"She has such a beautiful soul," says Ryan, co-founder of NKore Biotherapeutics. "When I heard it was Hamish my heart dropped to my stomach."

Related: Youngest Person to Explore 'Titanic' Site Details 'Safety Issues': 'I Fell Unconscious'

Ryan did all she could to assist in the search for Hamish, including enlisting the help of Congressman Eric Swalwell. She tells PEOPLE Swalwell was on the phone “for two days” as he attempted to get the Magellan sub deployed in the search area.

"This was really more of an effort for me to try and help the family get answers faster,” Ryan explains.

Aaron Newman, who was previously a mission specialist on the Titan, says he met Hamish before the Titan’s final voyage. He describes Hamish as “a real explorer” who was familiar with going on extreme adventures.

“He just was loving to explore and push the limits of humans and do conservation,” Newman tells PEOPLE. “So it wasn't just adventure and exploration, but he did a lot around conservation as well and helping the planet.”

Related: Friend of ‘Titan’ Sub Victim Paul-Henri Nargeolet Says He Died ‘In a Place He So Loved’

During their final conversation, Newman says, Rush offered him advice about his trip to the Mariana Trench — known as the deepest oceanic trench on Earth — in the Western Pacific Ocean.

“He was an incredible advisor about some of these trips,” Newman explains, adding that Rush “was easy to get in touch with” and seemed “happy to help as he could.”

Part of Rush’s goal in creating the Titan was to “democratize the sea and open it up to individuals” says Hagen, who adds that he wouldn't describe the passengers as "tourists."

“These are mission specialists who are passionate about science,” Hagen tells PEOPLE. “They’re passionate about history, and they’re passionate about recording the condition and deterioration of the iconic shipwreck known as the Titanic.”

In the aftermath of the Titan's implosion, announced by the U.S. Coast Guard on June 22, questions have mounted about the safety of the Titan and whether it should have gone underwater.

“This was a catastrophe that should never have happened, period," McLaren says.

With reporting by KIRSTY HATCHER, WENDY GROSSMAN KANTOR, JP MANGALINDAN, SIMON PERRY and MARISA SULLIVAN

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