In April 2019, Karl Stanley, who runs his own deep-sea exploration company in Honduras, took a 12,000-foot plunge inside the Titan off the coast of the Bahamas and said he heard a large cracking sound during the two-hour dive.
The New York Times reported that Stanley shared his concerns with OceanGate CEO Stockton Rush in emails in which he said that the sounds revealed were "an area of the hull that is breaking down."
In follow-up emails obtained by Insider, Rush sought to reassure Stanley that the issue with the noises was being looked at and suggested that it was improving, albeit with a caveat: "Our analysis of the past dives shows a definite reduction in acoustic events, but only having data from two full operating depth dives does not make for much of a validating trend."
The CEO added that the company was shooting for "as many as 5" more 4,000-foot dives to get more data on the acoustics.
Several days later, Stanley responded with "a few thoughts," including how "2-7 dives to operating depth are too few to launch an expedition selling 6 figure tickets in the middle of the ocean."
Tickets to visit the Titanic shipwreck on the Titan submersible cost up to $250,000.
"I think 50 is a good #," Stanley wrote, citing the number of tests he conducted with his submersible vessel, C-BUG, which stands for Controlled Buoyancy Underwater Glider. According to a magazine profile of Stanley, C-BUG was first designed to reach a maximum depth of 725 feet. Stanley now operates a vessel that can descend about 2,000 feet below sea level.
The Titan, in comparison, was advertised to reach depths of more than 13,000 feet.
Stanley offered another analogy with skydiving: 50 is the same number required to receive what's known in the sport as a "B license." The submersible expert also reiterated his concern about the hull.
"I think that hull has a defect near that flange, that will only get worse. The only question in my mind is will it fail catastrophically or not," Stanley wrote.
In response, Rush told Stanley that more tests would be conducted, but the CEO dismissed the idea of conducting 50 tests and said that the parachute-training analogy was a poor comparison.
"I suspect no deep diving sub did 50 MOD dives before non-essential crew were taken," Rush said.
Rush argued that Stanley's suggestion was an "arbitrary dive number" and said that testing "may take 2 dives or 20." But Stanley pushed back, saying that he came to the number based on his experience and that other experts agreed it was a "good indicator."
Towards the end of his salvo with Rush, Stanley wrote:
"I don't think if you push forward with dives to the Titantic this season it will be succumbing to financial pressures, I think it will be succumbing to pressures of your own creation in some part dictated by ego to do what people said couldn't be done."