Titan sub: Five men on board described as 'true explorers' - here are their stories

Tributes are being paid to the five men who were killed after the missing Titan sub suffered a "catastrophic implosion".

Three British citizens were on board the small vessel, with Foreign Secretary James Cleverly describing their loss as "tragic news".

A renowned Titanic expert and an adventurer who held world records are among those who took the ill-fated voyage. Here are their stories.

Hamish Harding

Mr Harding was a 58-year-old British billionaire who proudly described himself as a world explorer.

Just before the trip, he announced that he was joining OceanGate Expeditions - the company that supplied the vessel - as a mission specialist.

He was based in the United Arab Emirates, where he worked as chairman for an aircraft brokering company called Action Aviation.

Mr Harding holds the Guinness world record for the fastest circumnavigation of the Earth via the North and South Poles by an aircraft - 46 hours, 40 minutes and 22 seconds.

The adventurer also holds the world record for the longest duration at full ocean depth by a crewed vessel.

In 2016, he accompanied former astronaut Buzz Aldrin to the South Pole, when Aldrin became the oldest person ever to reach the Antarctic region at the age of 86.

And last year, he also took part in the fifth human space flight by Blue Origin - an American aerospace company founded by Jeff Bezos.

Paying tribute to Mr Harding, The Explorers Club described him as a "dear friend" who "continued to push dragons off maps both in person and through supporting expeditions and worthy causes".

Read more: What happened to the Titan sub

Shahzada and Suleman Dawood

Both British citizens, Shahzada and Suleman Dawood were father and son - and members of one of Pakistan's most prominent families.

Their firm - Dawood Hercules Corp - invests across the country in agriculture, petrochemicals and telecommunication infrastructure.

Based in the UK, Mr Dawood was a trustee at the SETI Institute, which searches for extraterrestrial intelligence.

The 48-year-old was also on the global advisory board at the Prince's Trust International - founded by King Charles to address youth unemployment.

Suleman, who was 19, had been studying at university.

Pakistani television channels interrupted their usual programming to announce they were feared dead.

Tributes have been paid by Pakistan's foreign ministry and government officials.

Salman Sufi, an adviser to Prime Minister Shahbaz Sharif, wrote on Twitter: "Very sad and unfortunate news. Prayers for the families of deceased. Mr Dawood and family are in our prayers."

Stockton Rush

Mr Rush was the CEO and founder of OceanGate, the company that began bringing tourists to the Titanic in 2021.

This was the Titan sub's third voyage, and he was serving as the vessel's pilot.

He became the world's youngest jet transport rated pilot at the age of 19, and flew commercial jets while in college.

In an interview with Sky News back in February, Mr Rush spoke about visiting the Titanic wreck.

"What really strikes you is how beautiful it is," he said. "You don't normally see that on a shipwreck. It is an amazingly beautiful wreck.

"You can see inside, we dipped down and saw the grand staircase and saw some of the chandeliers still hanging."

Mr Rush said he was motivated by a desire to document the Titanic's slow deterioration "before it all disappears or becomes unrecognisable".

Concerns had been raised about whether the Titan sub was safe because it lacked international certification - but the entrepreneur had argued that regulators were holding his company back and stifling innovation.

And in other interviews, he warned that nothing was without risk - but an experienced pilot like himself could avoid some common dangers.

"What I worry about most are things that will stop me from being able to get to the surface - overhangs, fish nets, entanglement hazard," Mr Rush told CBS News last year.

Greg Stone - an ocean scientist and friend of the businessman - said: "Stockton was a risk-taker. He was smart. He was, he had a vision, he wanted to push things forward."

Paul-Henri Nargeolet

Mr Nargeolet was a former commander who served in the French navy for 25 years.

During his service, he became the captain of the deep submergence group of the navy.

After leaving the navy, he joined the French Institute for Research and Exploitation of the Sea.

Mr Nargeolet had completed more than 35 dives to the Titanic site, and supervised the recovery of over 5,000 artefacts.

The first British diver to visit the wreckage called him as an "extraordinary explorer and an incredible individual" who knew the area better than anyone else.

But admitting there were risks, Dik Barton added: "It's an incredibly hostile environment at the depths we are talking about. The pressure down there is 2,500lbs per square inch, that's the equivalent of two adult elephants on your thumbnail.

"If something goes wrong, it goes wrong very quickly."

Like Mr Harding, Mr Nargeolet had also been a member of The Explorers Club, which described him as "one of the foremost experts on submersible expeditions to the Titanic".

The club's president, Richard Garriott de Cayeux, added: "They were both drawn to explore, like so many of us, and did so in the name of meaningful science for the betterment of mankind. They pushed themselves in their entrepreneurial pursuits as they did in exploration."