What do we know about the missing passengers on the Titan submersible?

It has been four days since the Titan submarine carrying five people went missing in the North Atlantic Ocean. The rescuers are racing against time to save the people onboard the submersible.

The 21-foot (6.5-metre) submersible disappeared on Sunday. It lost contact with its parent vessel about 900 miles (1,450 kilometres) east of Cape Cod, Massachusetts.

Since then, experts and teams from around the world have been scouring the depths of the ocean to look for the submarine. They do not have a lot of time, as the submersible is expected to run out of oxygen soon. Several media reports have claimed that the passengers have less than 10 hours left.

The missing passengers include a British adventurer, a French diver, a Pakistani father and son, and the founder of OceanGate Expeditions, the firm that conducts tours to the Titanic wreckage site.

What do we know about the passengers?

British-Pakistani businessman Shahzada Dawood is the vice chairman of Engro Corp., a Pakistan-based conglomerate. He boarded the submarine with his 19-year-old son, Suleman Dawood, said his family in a statement. His family says that even they have only "limited information" about the rescue operation.

Paul-Henri Nargeole, a 77-year-old and expert on the Titanic, is also one of the passengers, per a Forbes report. He has appeared in several documentaries on the Titanic.

British mogul Hamish Harding is another noteworthy passenger onboard the submarine. He is the chairman of the British aircraft company Action Aviation. It also needs to be noted that this is not the first time that Harding has been a part of such an expedition.

He also flew on Jeff Bezos' Blue Origin space flights and has a record for flying around the world and deep-sea diving. He had even tweeted about his Titan dive just a day before he left for the trip.

"I am proud to finally announce that I joined @OceanGateExped for their RMS TITANIC Mission as a mission specialist on the sub going down to the Titanic," read the tweet posted by Harding.

The CEO OceanGate Inc., Stockton Rush, is also thought to be on board the vessel. A New York Times report has even claimed that his wife is a descendant of two first-class passengers who died when the mighty Titanic sank in 1912. Rush was the one who was piloting the submersible before it lost contact.

The rescuers have until around midday on Thursday to find the missing passengers. The US Coast Guard, Canadian military planes, and French vessels have all come together for the multinational operation. Meanwhile, remote-operated robots have also been deployed for undersea search operations.

The submarine could possibly be stuck 12,500 feet down on the ocean floor, according to media reports. Accessing such depths is as tough as planning a trip to space. Low oxygen levels and high underwater pressure only make deep-sea operations difficult.

The fascination with the Titanic:

It has been over a century since the sinking of the Titanic, but the fascination with the ship and its story has not died down. People are willing to spend millions just to get a glimpse of its wreckage lying in the North Atlantic.

Its tragic end has been immortalised by the Oscar-winning film of the same name. Released in 1997, James Cameron's romantic drama recounted the 1912 disaster of the RMS Titanic, which sank during its maiden voyage from Southampton to New York City, killing 1,517 people.

Interspersed with the harrowing events is the love story of a young Rose DeWitt Bukater and Jack Dawson, played by Kate Winslet and Leonardo DiCaprio, who become embroiled in a whirlwind romance aboard the "unsinkable ship."

The film was a global phenomenon, going on to scoop up eleven Oscars. These included Best Picture, Best Cinematography for Russell Carpenter, Best Original Score for James Horner, a slew of technical awards and Best Director for Cameron.