The five people who were aboard a submersible that went missing while on an expedition to explore the wreckage of the Titanic did not survive, according to the company that arranged the trip. 

The passengers on the 21-foot sub were British businessman Hamish Harding; Pakistani businessman Shahzada Dawood and his teenage son, Suleman; French explorer Paul-Henri Nargeolet; and Stockton Rush, CEO of OceanGate, the company that operates the vessel.

"We now believe that our CEO Stockton Rush, Shahzada Dawood and his son Suleman Dawood, Hamish Harding, and Paul-Henri Nargeolet have sadly been lost," OceanGate said in a statement to CBS News. "These men were true explorers who shared a distinct spirit of adventure, and a deep passion for exploring and protecting the world's oceans."

OceanGate had billed the trip as a chance to "become one of the few to see the Titanic with your own eyes." Securing a seat on the vessel cost $250,000, according to the company, which touted the trip not as mere tourism but as a dive with a scientific purpose.

Last year, Rush told CBS News that the tours attract people of all income levels despite the high sticker price. "We've had people who have mortgaged their home to come and do the trip. And we have people who don't think twice about a trip of this cost," he said.

In a June 17 Facebook post, Harding announced he was "proud" to be joining the expedition. 

"The team on the sub has a couple of legendary explorers, some of which have done over 30 dives to the RMS Titanic since the 1980s including PH Nargeolet," he noted. 

Here's what to know about the passengers who were aboard the sub.

Hamish Harding, chairman of Action Aviation

Harding was the chairman of a company called Action Aviation, which sells aircraft to Fortune 100 companies, international corporations, heads of state and people in the entertainment and sports industries, according to its website. 

The British businessman is referred to as a billionaire in the British press, but Forbes magazine noted that he's not included on its list of the world's richest people. 

Aside from his business, Harding was known for his exploits as an adventurer. He held several records with the Guinness Book of World Records, including "fastest circumnavigation of Earth via both the geographic poles" by airplane, which he and a team accomplished in 2019 in a little over 46 hours. 

Harding also was one of six people on Jeff Bezos-owned Blue Origin's mission last June, when they flew to the edge of space.

Before the Titanic expedition, Harding shared on Facebook that the mission was "likely to be the first and only manned mission to the Titanic in 2023" because of weather conditions. 

In an interview two years ago, Harding acknowledged the risks and dangers of underwater expeditions after he had traveled with U.S. explorer Victor Vescovo more than two and a half miles along the floor of the Mariana Trench, 35,876 feet below the sea surface. 

"The only problem is that there is no other sub that is capable of going down there to rescue you," he said of that journey. "[H]aving four days of supply doesn't make a difference really. If something goes wrong, you are not coming back."

In a statement on Tuesday, Action Aviation Managing Director Mark Butler said the company and Harding's family are "very grateful for all the kind messages of concern and support from our friends and colleagues."

Shahzada Dawood and his son, Suleman Dawood

Shahzada Dawood, who was 48, was the vice chairman of Dawood Hercules, an investment and holding company based in Karachi, Pakistan.

Dawood Hercules is part of the Dawood Group, a family business for more than a century, according to his biography at the SETI Institute, where he also served on the board. Dawood was heir to one of Pakistan's largest family fortunes, according to the New York Times.

"Our deepest condolences to the Dawood family and the family of other passengers on the sad news about the fate of Titanic submersible in the North Atlantic," Pakistan's Foreign Ministry wrote on Twitter Thursday. "We appreciate the multinational efforts over the last several days in search of the vessel."

Dawood was a resident of the U.K. with his wife and two children, Suleman and daughter Alina, the SETI Institute noted. He was also an "ardent animal lover" and had a master's degree in global textile marketing from Philadelphia University in the U.S. and a law degree from Buckingham University in the U.K.

Suleman Dawood was 19 years old, according to the U.K.'s DailyMail. He was a science fiction fan and also enjoyed solving Rubik's Cubes and playing volleyball, according to DH Group & Engro Corporation, part of the Dawood Hercules Group.

"We are very grateful for the concern being shown by our colleagues and friends and would like to request everyone to pray for their safety," the Dawood family said in a statement.

Paul-Henri Nargeolet, "Titanic's Greatest Explorer"

Nargeolet was known as a Titanic expert, according to the OceanGate website. He led six expeditions to the ship's wreckage site and was known as "Titanic's Greatest Explorer," the company said. 

Nargeolet was also the director of underwater research for RMS Titanic, an American company that owns the salvage rights to the wreck and operates exhibits featuring artifacts from the ship. About 30 million people have visited its exhibits, according to the company.

In an interview with CBS News this week, G. Michael Harris, founder of RMS Titanic, said that he has worked with Nargeolet for the past 30 years, describing him as an "all-around good guy." 

Stockton Rush, CEO of OceanGate

Rush, the CEO of the company running the expedition, was also the sub's pilot.

When he was 19, Rush was the youngest person to become a jet transport-rated pilot when he earned a DC-8 Type/Captain's rating at the United Airlines Jet Training Institute, according to his biography at OceanGate.

Rush earned a bachelor's degree in aerospace engineering from Princeton University in 1984 and an MBA from the Berkeley Haas School of Business in 1989. In 2009, Rush founded OceanGate, where he oversees the company's financial and engineering strategies, according to the company.

Rush told CBS News' David Pogue last year that OceanGate still hadn't turned a profit. 

"People might say, 'Hey, that's a lot of money, $250,000.' But we went through over a million dollars of gas," he said.

— CBS News' Emmet Lyons contributed to this report.

In:
• North Atlantic
• RMS Titanic
• Submarine
• OceanGate
• Atlantic Ocean
• Submersible