What you need to know about the 5 passengers on the missing Titanic sub

Hamish Harding, chairman of Action Aviation:

Harding is 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 is not included in the list of the world's richest people.

In addition to his business, Harding is known for his adventures as an adventurer. He holds several Guinness World Records, including the "fastest circumnavigation of the Earth across both geographic poles" by aircraft, which he and a team achieved in 2019 in just over 46 hours.

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

Before the Titanic expedition, Harding shared on Facebook that the mission "will likely be the first and only crewed mission on Titanic in 2023" due to weather conditions.

In an interview two years ago, Harding acknowledged the risks and dangers of underwater expeditions after traveling more than two and a half miles along the bottom of the Mariana Trench, 35,876 feet below sea level, with American explorer Victor Vescovo.

"The only problem is there's no other submarine that can get there to save you," he said of the trip. "[H]our four days supply doesn't really matter. If something goes wrong, you don't come back."

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

"We look forward to welcoming him home," Butler wrote.

Shahzada Dawood and his son, Suleman Dawood:

Shahzada Dawood, 48, is 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 serves on the board. Dawood is the heir to one of Pakistan's largest family fortunes, according to the New York Times.

Dawood is a resident of the United Kingdom with his wife and two children, Suleman and daughter Alina, the SETI Institute noted. He is also a "keen animal lover" and holds a master's degree in global textile marketing from Philadelphia University in the US and a law degree from Buckingham University in the UK.

According to the British DailyMail, Suleman Dawood is 19 years old. According to DH Group & Engro Corporation, part of the Dawood Hercules Group, he is a fan of science fiction and also enjoys solving Rubik's cubes and playing volleyball.

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

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

He is also the director of underwater research for RMS Titanic, an American company that owns the rights to salvage the wreck and operates exhibits featuring artifacts from the ship. According to the company, about 30 million people visited its exhibitions.

In an interview with CBS News, G. Michael Harris, founder of RMS Titanic Inc., said Tuesday that he had worked with Nargeolet for the past 30 years and described him as an "all-around good guy."

Stockton Rush, CEO of Ocean Gate:

Rush, the CEO of the company operating the expedition, is also the pilot of the missing Titan expedition.

At age 19, Rush was the youngest person to become a jet airline pilot when he earned a DC-8/Captain rating at the United Airlines Jet Training Institute, according to his biography on Ocean Gate.

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 Ocean Gate, where he oversees the company's financial and engineering strategies, according to the company.