A pal of tragic Titanic explorer Hamish Harding told the Briton he "shouldn’t get in that damn sub".
The revelation came as police in Canada refused to rule out a criminal investigation into the ill-fated expedition that saw five men - including three Brits - lose their lives.
The OceanGate 'Titan' submersible the tourists descended to the wreck of the Titanic in suffered a “catastrophic implosion” close to the sea bed killing all those onboard instantly.
Billionaire adventurer Harding, 58, Pakistani-British businessman Shahzada Dawood, 48, his son Suleman Dawood, 19, French underwater explorer Paul-Henri Nargeolet, 77, and OceanGate founder Stockton Rush, 61, all perished.
Hamish’s friend Victor Vescovo, one of the world’s most accomplished deep sea pilots, told how the Brit was determined to go on the sub.
"Hamish asked to go to the Titanic in my submersible, and that’s not something I do, plus it would cost millions of dollars,” he said.
"When Stockton was able to succeed in taking people down in his, Hamish became set on it.
"I talked to Hamish about it, and I told him he shouldn't get in that damn sub.
"It was only a matter of time before they [Ocean-Gate] kill somebody.
"But Hamish really, really wanted to go to the Titanic and that was the only opportunity ... now it's ‘Damn, why didn't I raise more fuss, should I have been more aggressive?’
"I had told Hamish my significant concerns about OceanGate's design and the safety and their operations.
"I think he probably thought about it when diving with me, but then he convinced himself they were improving and maybe that people like me were too conservative or that it was worth the risk.
"He decided to roll the dice. I was surprised Hamish went. He texted me from the ship saying ‘I’m going down tomorrow to Titanic’.
"The attitude I had was ‘OK, I've said my piece ... that was the last text.’"
Rob McCallum, an expert in deepwater submersibles, described Rush as a "lone wolf".
"People are captivated by the wreck and the story and it drew in Hamish too," he said.
"But OceanGate were the last kids to arrive at the table and had by far the worst possible set-up - the only operator not classed. Stockton Rush was a lone wolf."
In 2018 Dave Lochridge, OceanGate's Scottish director of marine operations, was fired after writing a devastating assessment of Titan.
He said small flaws in the carbon fibre hull could become major tears during the huge pressure changes experienced during descent and ascent.
On Saturday, as the Titan’s mothership ship Polar Prince returned to port in St John’s, police Superintendent Kent Osmond said law enforcement was in the early stages of the probe.
“Following the US Coast Guard’s announcement earlier that debris from the submersible was located and all five on board were presumed dead, we will now look at the circumstances that led to those deaths,” Osmond said.
“Such an investigation will proceed only if our examination of the circumstances indicate criminal, federal or provincial laws may possibly have been broken.”
Osmond added the initial team of investigators would look into whether a full investigation is warranted or not.
French and British authorities assisted the US and Canadian Coast Guard in a search and rescue mission for four days after the OceanGate Expeditions submersible went missing on June 18.
It took the crew of the Polar Prince eight hours to alert the coastguard.
Experts say the Titan submersible would not have passed strict safety protocols in the US and Canada, but as it operated in international waters, it did not fall under their jurisdiction.
