Search teams are racing against time to find a tourist submersible that went missing during a dive to the Titanic’s wreck on Sunday.
Five people were onboard when contact with the small sub was lost about an hour and 45 minutes into its dive.
The rescue operation is continuing overnight in the mid-Atlantic but there has been no sign so far of the vessel.
US and Canadian agencies, navies and commercial deep-sea firms are all helping the rescue operation.
As of Monday afternoon, it was thought the crew members had roughly four days of oxygen left at most. Among them is theBritish billionaire businessman and explorer Hamish Harding.
Pakistani businessman Shahzada Dawood and his son, Suleman, were also on board, their family said in a statement.
French explorer Paul-Henry Nargeolet is thought to be on board, according to a Facebook post by Mr Harding before the dive started
Stockton Rush, chief executive of OceanGate – the firm behind the dive – is also being widely reported to be on the vessel.
“Right now, our focus is on getting as much capability into the area as we can,” Rear Adm John Mauger of the US Coast Guard told a press conference.
Military planes, a submarine and sonar buoys have so far been used in the search for the vessel.
Titanic’s wreck lies some 435 miles (700km) south of St John’s, Newfoundland, though the rescue mission is being run from Boston, Massachusetts.
The US Coast Guard said a research ship called the Polar Prince had conducted a surface search for the sub on Monday evening. It is used to transport submersibles to the wreckage site and was the support ship on Sunday’s tourist expedition.
The missing craft is believed to be tour firm OceanGate’s Titan submersible, which CBS journalist David Pogue travelled aboard last year to reach the wreckage of the Titanic.
Hehas told the BBCthat when the support ship is directly above the sub, short text messages are able to be sent between the two.
Otherwise, communication via GPS or radio systems is not available as neither work underwater.
Pogue says it is also not possible for those aboard the sub to escape by themselves because they are sealed inside by bolts applied from the outside.
A submersible vessel is different to a submarine. According to the National Oceanic and Atmospheric Administration, a submarine can launch itself into the ocean from a port independently, while a submersible has very limited power reserves so needs a mother ship that can launch it and recover it.
Rear Adm Mauger noted the area in which the search was taking place was “remote”, making operations difficult.
Added to this is the fact that visibility is quickly lost below the surface of the water as light cannot penetrate far.
The OceanGate website lists three submersibles it owns, and only the Titan is capable of diving deep enough to reach the Titanic wreckage.
The vessel weighs 23,000 lbs (10,432 kg) and, according to the website, can reach depths of up to 13,100 ft.
Tickets cost $250,000 (£195,000) for an eight-day trip including dives to the wreck at a depth of 3,800m (12,500ft).
On social media at the weekend, Mr Harding said he was “proud to finally announce” that he would be aboard the mission to the wreck of the Titanic – but added that because of the “worst winter in Newfoundland in 40 years, this mission is likely to be the first and only manned mission to the Titanic in 2023”.
He later wrote: “A weather window has just opened up and we are going to attempt a dive tomorrow.”
OceanGate said it had “been unable to establish communications with one of our submersible exploration vehicles” but that its “entire focus [was] on the crewmembers in the submersible and their families”.
“We are deeply thankful for the extensive assistance we have received from several government agencies and deep sea companies in our efforts to re-establish contact with the submersible,” it added.
The company bills the eight-day trip on its carbon-fibre submersible as a “chance to step outside of everyday life and discover something truly extraordinary”.
It sets sail from St John’s in Newfoundland, with each full dive to the wreck, including the descent and ascent, reportedly taking around eight hours.
According to its website, one expedition is ongoing and two more have been planned for June 2024.
The Titanic, which was the largest ship of its time, hit an iceberg on its maiden voyage from Southampton to New York in 1912. Of the 2,200 passengers and crew onboard, more than 1,500 died.
Its wreckage has been extensively explored since it was discovered in 1985.
The wreck lies in two parts, with the bow and the stern separated by about 2,600ft. A huge debris field surrounds the broken vessel.
Last month,the first full-sized digital scan of the wreck was created using deep-sea mapping. The scan shows both the scale of the ship, as well as some minute details, such as the serial number on one of the propellers.
Source: BBC News