Five people are on board the submersible tourist vessel which went missing during a voyage to the Titanic shipwreck off the coast of Canada, as a major search and rescue mission works around the clock to locate the Titan.
British-Pakistani businessman Shahzada Dawood and his son Suleman are on the vessel with French submersible pilot Paul-Henri Nargeolet, chief executive of OceanGate Expeditions Stockton Rush, and British billionaire and pilot Hamish Harding.
- Shahzada and Suleman Dawood
The father and son belong to one of Pakistan's most prominent families.
Shahzada Dawood, 48, is vice-chairman of Pakistani conglomerate Engro Corporation, and a long-time adviser to the King's charity, Prince's Trust International, with a focus on its work in Pakistan.
He lives in Surbiton, south-west London, with his son, wife Christine and daughter Alina, according to the Telegraph.
A family statement reported by the BBC said Shahzada was interested in "exploring different natural habitats", and had previously spoken at both the United Nations and Oxford Union.
They described Suleman as a "big fan of science fiction literature and learning new things", with an interest in Rubik's Cubes and playing volleyball.
It is understood that the family were already spending a month in Canada before Shahzada and Suleman made the dive.
Neighbours of the family told the Telegraph they were "very good neighbours, nice interesting people" and said Suleman is was 19.
With an LLB in Law from the University of Buckingham and an MSc in Textile Marketing from Philadelphia University, Shahzada has held several trustee and director roles across several companies.
He became a director of the Dawood Hercules Corporation in 1996, and served as vice chairman between 2018 to 2021, according to his LinkedIn profile. The company is an investment holding platform, of which Engro Corporation is a subsidiary.
Alongside his work in business, he is also a supporter of the British Asian Trust, an organisation which tackles poverty in South Asia, and a trustee of the Seti Institute, a research organisation in California which searches for extra-terrestrial life.
Shahzada's father, Hussain Dawood, was a founding patron of Prince's Trust International, according to the charity.
- Stockton Rush
The chief executive and founder of OceanGate Expeditions, Stockton Rush originally trained as a pilot, becoming the youngest jet transport-rated pilot in the world aged 19 in 1981, according to his profile on the OceanGate website.
He graduated from Princeton with a degree in aerospace engineering in 1984, the profile says.
Wendy Rush, nee Weil, is his wife, with their 1986 wedding announcement published in the New York Times. Ms Weil is listed as the director of communications for OceanGate and a "comms and tracking team member" for the Titanic expedition on her LinkedIn page.
Mr Rush was described as "highly professional" alongside pilot Paul-Henri Nargeolet by a businessman who Mr Rush led on a previous visit to the Titanic wreck.
Oisin Fanning told BBC Radio 4 that the two men were "consummate professionals" who had made the journey to the Titanic "38, 40 times".
He added: These are not fly-by-nighters, these are very highly professional people."
Mike Reiss, a writer and producer of The Simpsons, described him as a "magnetic man" who is "the last of the great American dreamers", the New York Times reported.
Mr Reiss, who went on a Titanic dive in a different OceanGate submersible with Mr Rush, also compared him to business magnates Henry Ford and the Wright brothers.
In a 2017 interview with the alumni magazine for Princeton University, where he studied mechanical aerospace engineering, he said: "I was interested in exploration. I thought it was space exploration. I thought it was Star Trek and 2001: A Space Odyssey and Star Wars . and then I realised, it's all in the ocean."
Having co-founded OceanGate in 2009, Mr Rush has led crewed expeditions to remote ocean locations including the Titanic.
He is also the founder and member of the board of trustees of the linked charity organisation OceanGate Foundation, which uses marine technology to develop understanding of marine science, history and archaeology.
Alongside this work, Mr Rush has also overseen development of a number of companies, experimental ventures and inventions, including serving on the board of directors for Seattle's BlueView Technologies, a manufacturer of small, high-frequency sonar, and as chair of Remote Control Technology Inc, producing wireless remote-control devices for companies including Boeing.
According to his Ocean Gate biography, he built his own aircraft, which he flew himself, and has undertaken over 30 dives in a modified two-man submersible.
He told Sky News in February that he was struck by how "beautiful" the Titanic was on a previous visit.
Mr Rush said: "What really strikes you is how beautiful it is. You don't normally see that on a shipwreck.
"It is an amazingly beautiful wreck."
- Paul-Henri Nargeolet
A former commander who served in the French navy for 25 years, Mr Nargeolet, 77, was in the first human expedition to visit the ship in 1987, according to the Telegraph.
After his career in the French navy, where he was captain of the deep submergence group, he held a number of roles in deep diving and piloting submersibles, including acting as director of DESM, noted on his LinkedIn profile as a French deep-diving equipment company.
Sky News reported that he joined the French Institute for Research and Exploitation of the Sea, after the navy, according to The Five Deeps Expedition - a company that assembles scientists, engineers and submersible operators for missions.
As director of the Underwater Research Programme with RMS Titanic Inc, which owns the rights to the Titanic wreck, he has led the retrieval of items from the ship across many expeditions.
He lives in Connecticut, US, while his adult children live in Cork, Ireland, the Telegraph has reported.
Born in Chamonix, France, he spent his childhood in Africa with his parents, according to the Daily Mail.
Mr Nargeolet was married to American newsreader Michelle Marsh until her death in 2017 aged 63, according to the New York Times.
He is an "extremely capable submersible operator pilot", his friend Dik Barton, the first British diver to see the Titanic wreck, told ITV's Good Morning Britain.
Mr Barton said Mr Nargeolet had been down to the Titanic wreck 37 times, referring to him as PH.
He added: "I have enormous respect for him and his ability, and, quite frankly, if there's anybody I'd ever want to be in a position, God forbid, in this circumstance then it would be PH.
"He will certainly be doing all he possibly can to make sure everyone is calm and collected and waiting for recovery."
Last year, Mr Nargeolet published a book in France about his experiences with the Titanic titled Dans Les Profondeurs Du Titanic (In The Depths Of The Titanic).
In an interview with the Irish Examiner in 2019, he said: "If you are 11 metres or 11 kilometres down, if something bad happens, the result is the same.
"When you're in very deep water, you're dead before you realise that something is wrong, so it's just not a problem."
- Hamish Harding
The billionaire pilot and chair of Action Aviation, a sales and operations company which manages private jet sales, shared on his Instagram account that he had joined the OceanGate expedition as a "mission specialist".
Mr Harding, 58, is based in the UAE where the Action Aviation HQ is located, and presents himself in personal social media biographies as a "world explorer".
His friend, the marine scientist James Mearn, characterised him as "very charming" and "very adventurous" in an interview with the BBC's World At One.
He was also described as the "quintessential British explorer" by his friend Colonel Terry Virts, a former commander of the International Space Station on the Today programme.
Colonel Virts said: ?? "Some people watch Netflix and some people play golf, and Hamish goes to the bottom of the ocean or into space or, you know, he sets world records flying around the planet.
"As I've said several times now, Hamish is the quintessential British explorer. He loves adventure. He loves exploring and that's just the kind of person he is."
Mr Harding was "very methodical", according to Colonel Virtz, who said: "I don't think Hamish is an adrenaline junkie at all."
According to multiple reports, he has two sons, named Rory and Giles, a stepdaughter named Lauren and a stepson, Brian Szasz, and his wife is called Linda.
On the Action Aviation website profile, Mr Harding writes that the company is the "professional representative of choice" for large aircraft transactions between heads of state, VIPs, Fortune 100 companies and international corporations".
Mr Harding holds several Guinness world records, including the fastest circumnavigation of the Earth via the North and South Poles by an aircraft, in 46 hours, 40 minutes and 22 seconds.
In March 2021, he was awarded the record for the longest time traversing the deepest part of the ocean on a single dive, alongside Victor Vescovo, at four hours and 15 minutes along the sea floor of Challenger Deep in the western Pacific Ocean.
In an interview with the Dubai-based Khaleej Times newspaper, Mr Harding said of this expedition: "I have always wanted to venture into uncharted territories. That got me interested in embarking on adventures and explorations, in general."
He said he often took his son Giles with him on these trips, including another world-record beating journey to the South Pole when Giles, aged 12, became the youngest person to have visited.
Last year, he also took part in the fifth human space flight by Jeff Bezos's aerospace company Blue Origin, according to Sky News.