A witness to the Titan submersible disaster has told BBC News about the fear and false hope felt by those on its support ship.

Rory Golden was on the Oceangate expedition when contact with the sub and its five passengers was lost on a dive to the Titanic in June 2023.

“We had this image in our heads of them being down there, running out of oxygen in the freezing cold, getting terribly frightened and scared,” he said.

But after learning the sub had imploded just hours into the dive, he said it was a comfort to know those onboard hadn’t suffered.

Mr Golden was on the Polar Prince support ship to give presentations about the Titanic when the submersible went missing.

“When the sub was overdue we weren’t unduly concerned because communications break down a lot in the ocean,” he explained.

“But when the alarm was finally raised, that’s when we realised that there were some serious issues.”

A major search and rescue operation was launched by the US Coast Guard.

A few days in, underwater sounds detected by search aircraft raised hopes that these were coming from the missing sub.

But it’s now known that those onboard most likely died instantly after Titan suffered a catastrophic failure as it neared the Titanic at the bottom of the Atlantic.

“We lived in false hope for four days,” Mr Golden said. “There’s still a lot of questions to be answered.”

Those who perished were British explorer Hamish Harding, the British-Pakistani businessman Shahzada Dawood and his son Suleman, Stockton Rush, the CEO of Oceangate, and French diver Paul Henri – or PH – Nargeolet.

Rory Golden was a close friend of PH – a veteran deep sea explorer. He is now on the first expedition to the Titanic since the tragedy – an expedition that PH Nargeolet was supposed to be leading.

A plaque is being laid in his honour at the wreck site and a memorial service for all those who died on the sub has been held at sea.

Mr Golden told the BBC he was one of the last people to see PH alive.

“He left the ship in great spirits, in great form and he was happy. He was going somewhere that he wanted to be.”

Rory Golden had also visited the Titanic on the Oceangate sub.

”PH and I had discussed the submersible in the past and I had actually made a dive in it myself the year before,” he said.

“And I’m here – as are many others. The Titan sub had made 15 dives to the Titanic up to that point, so it had worked.

“I was comfortable, I spent 12 hours at the Titanic and it was a whole different experience being in a submersible that I could actually move around quite well in.”

He told the BBC that he didn’t regret his dive at all.

“It wasn’t my time,” he said. “You never know when your time is going to come. And that certainly brought that home to all of us.”

The discovery of the wreckage of Titan four days after it went missing confirmed the fate of those onboard.

“We all cried when the remains were found of the sub,” he said.

“A special bond has been formed between all of us who were there on the ship that week. And that’s a bond that will always be there.”

Industry experts had raised many serious questions about the safety of the Titan submersible prior to the dive.

Investigations by the US Coast Guard and Canadian Coast Guard are still ongoing.

They are likely to call for changes to ensure such a tragedy doesn’t happen again.