A British-based father and his son have been confirmed as passengers on the submersible that went missing on a dive to the wreck of the Titanic.
Shahzada Dawood, 48, and his son Sulaiman Dawood, 19, were on board the submarine-like boat taking paying tourists to view the famous wreck, which lies 12,500ft beneath the surface of the Atlantic Ocean, 370 miles off the coast of Newfoundland, Canada.
The family of Shahzada Dawood said in a statement: "Our son Shahzada Dawood and his son, Suleman, had embarked on a journey to visit the remnants of the Titanic in the Atlantic Ocean.
"As of now, contact has been lost with their submersible craft and there is limited information available."
The Pakistani nationals are both understood to live in Surrey, in the UK.
The statement continued: "We are very grateful for the concern being shown by our colleagues and friends and would like to request everyone to pray for their safety while granting the family privacy at this time.
"The family is well looked after and are praying to Allah for the safe return of their family members."
Mr Dawood is a business advisor who also serves on the board for Prince's Trust International.
The MailOnline reports that the Dawood family are amongst the richest in Pakistan but have strong links to the UK and Shahzada is believed to live in a Surrey mansion with his wife Christine, son Sulaiman and daughter Alina.
The crew set out on Friday and according to the Coast Guard, the craft submerged Sunday morning, and its support vessel, the Canadian research icebreaker Polar Prince, lost contact with it about an hour and 45 minutes later.
British businessman Hamish Harding, who lives in Dubai, is another one of the five people missing.
The 58-year-old chairman of aircraft firm Action Aviation is a renowned explorer who has flown to space and holds three Guinness World Records.
His stepson Brian Szasz said in a now-deleted post on Facebook: He "has gone missing on (the) submarine."
It is believed that four of the people are tourists and one is the pilot of the submarine.
Rescuers are understood to be in a "race against time" to reach the small vessel, which has only a limited supply of oxygen.
It is understood there is enough oxygen on the vessel to last about 96 hours and the vessel went below the surface about 48 hours ago.
The submarine is run by OceanGate Expeditions, a private company, which charges $250,000 (£195,250) for a package to visit the Titanic.
Rear Admiral John Mauger, a commander for the U.S. Coast Guard, said additional resources would arrive in the coming days.
“It is a remote area — and it is a challenge to conduct a search in that remote area," he said. "But we are deploying all available assets to make sure we can locate the craft and rescue the people on board.”
Unlike submarines that leave and return to port under their own power, submersibles require a ship to launch and recover them.
OceanGate hired the Polar Prince to ferry dozens of people and the submersible craft to the North Atlantic wreck site. The submersible would make multiple dives in one expedition.
Alistair Greig, a professor of marine engineering at University College London, said submersibles typically have a drop weight, which is "a mass they can release in the case of an emergency to bring them up to the surface using buoyancy."
"If there was a power failure and/or communication failure, this might have happened, and the submersible would then be bobbing about on the surface waiting to be found", Greig said.
Another scenario is a leak in the pressure hull, in which case the prognosis is not good, he said.
He explained: "If it has gone down to the seabed and can’t get back up under its own power, options are very limited.
"While the submersible might still be intact if it is beyond the continental shelf, there are very few vessels that can get that deep, and certainly not divers."
Even if they could go that deep, he doubts they could attach to the hatch of OceanGate's submersible.
