Authorities say the pilot and four passengers of the submersible Titan disappeared while on a mission to discover the wreck of the presumed dead Titanic.

Billionaire British adventurer Hamish Harding, UK citizen Shahzada Dawood and his 19-year-old son Suleman Dawood, French citizen Paul-Henri Nargeolet and OceanGate Expeditions chief executive Stockton Rush have been “significantly missing” sad,” the company announced.

The US Coast Guard has sent its “deepest condolences” to the families after the ship’s stern was found about 1,600 feet from the bow of the Titanic wreck.

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The exploration company said there was a “catastrophic explosion” in Titan’s pressure chamber.

It added: “These men are true explorers who share a distinct spirit of adventure and a deep passion for discovering and protecting the world’s oceans.

“Our hearts go out to these five souls and every member of their family during this tragic time.

“We grieve the loss of lives and the joy they brought to those they knew.”

Here’s what is known about the five people on board:

Hamish Harding

Hamish Harding, 58, president of private jet airline Action Aviation, posted on social media that he was proud to be on board the Titanic as a “mission expert”, adding: “Due to the bad winter worst in Newfoundland in 40 years, this mission is likely to be the first and only manned mission to Titanic in 2023.”

He has previously traveled to the ocean floor on Challenger Deep and into space on Jeff Bezos’ Blue Origin.

The father-of-two is a seasoned explorer and has held three Guinness World Records, including the longest time spent in the ocean depths entirely by a manned ship. He dived to the lowest depth of the Mariana Trench in March 2021.

Dubai-based Mr Harding also joined the 2019 “One More Orbit” flight mission that set the record for the fastest circumnavigation of the Earth by plane over both geographic poles.

“He doesn’t stand still. Jannicke Mikkelsen, an adventurer and friend, said if he’s not working hard, he’s exploring hard.

Paul-Henri Nargeolet

French diver Paul-Henri Nargeolet, 77, is the director of underwater research for a company that owns the rights to the wreck of the Titanic and recovers the artifacts.

A former commander in the French navy, he was both a deep diver and a minesweeper. After retiring from the navy, he led the first Titanic salvage expedition in 1987 and many more, becoming the top authority at the wreck site.

OceanGate describes Mr. Nargeolet as “Titanic’s greatest explorer”.

The former naval officer was born in Chamonix, France, but spent his early years in Africa with his parents. He was married to American newsreader Michelle Marsh until her death in 2017.

He completed 35 dives in the submersible. In a 2020 interview, he talked about the dangers of deep diving, saying, “I’m not afraid to die, I think one day it will.”

Pakistani businessman Shahzada Dawood and his son Suleman

Shahzada Dawood, 48, and son Suleman Dawood, 19, are UK citizens, and are believed to have lived in a mansion in Surrey with Mr Dawood’s wife Christine and daughter Alina.

Shahzada Dawood served as vice president of one of Pakistan’s largest conglomerates, Engro Group, with investments in fertilizer, vehicle manufacturing, energy and digital technology.

According to a statement from the Dawood Group, his interests include wildlife photography, gardening and exploring natural habitats, while Suleman is a fan of science fiction literature. He studied at the University of Strathclyde.

Stockton fever

Stockton Rush, 61, chief executive officer of OceanGate Expeditions, told Sky News earlier this year that the Titanic was “a stunningly beautiful wreck”.

His company, which provides manned diving services to researchers and deep-ocean explorers, operated the doomed submersible Titan.

Mr. Rush began his pilot career at the age of 19 after qualifying from the United Airlines Jet Training Institute. He is the youngest jet pilot in the world.

According to Mr. Rush story on his company’s website, he graduated from Princeton University with a BSE in aerospace, aeronautical and spaceflight engineering in 1984.

He then joined the McDonnell Douglas Corporation as a flight test engineer and spent two years at Edwards Air Force Base.

He serves on the Board of Directors of the Museum of Flight, the board of the enterprise software company Entomo, and is president of Remote Control Technology.

In 2012, Mr. Rush also founded the non-profit OceanGate Foundation while sitting on the board of BlueView Technologies, a manufacturer of high-frequency sonar systems.

The company behind the doomed venture

OceanGate Expeditions offers 8-day tours to see the wreck of the Titanic at a cost of $250,000 per person.

It says it uses next-generation manned submersibles and launchers to increase access to oceans as deep as 4,000 meters.

OceanGate’s website says: “OceanGate has successfully conducted more than 14 expeditions and over 200 dives in the Pacific, Atlantic and Gulf of Mexico.

“After each mission, the team reviews and updates the processes as part of their commitment to continuously evolving and ensuring operational safety.”

Her submersibles were launched from a mother ship, which later salvaged them at the end of the mission.

The Titanic, operated by the White Star Line, sank during its maiden voyage across the Atlantic Ocean in 1912.

The ship, the largest ship at the time, departed Southampton on 10 April 1912, with more than 2,200 passengers and crew on board, bound for New York City.

Five days after the voyage, the Titanic hit an iceberg and sank to the bottom of the ocean. More than 1,500 people died.

The wreck remained undiscovered, until 1985 it was found at a depth of about 12,500 feet on the bottom of the Atlantic Ocean, about 370 miles off the coast of Newfoundland, Canada.

In recent years, trips to visit it have become more and more popular.