Oxygen is now feared to have run out on the missing Titanic submersible but a fleet of rescue ships are still searching for the vessel.
The rescue mission which involves robot subs and a US Navy CURV21 are hoping to find the lost Titan craft and pull it to the surface.
A deep water robot sub has reached the Atlantic floor while another is descending the 12,500ft of ocean - just as the oxygen deadline passed.
The OceanGate sub's air supply is thought to have run out around 12pm today UK time.
The rescue mission which involves robot subs and a US Navy CURV21 are hoping to find the lost Titan craft and pull it to the surface
Reuters
Five specialist vessels backed by deep-sea robots and search-and-rescue aircraft were already searching a vast 15,000 square mile zone up to a depth of two and a half miles.
The number of rescue vessels were set to double before the air supply deadline.
Canada’s CGS Ann Harvey, CGS Terry Fox, Motor Vessel Horizon Arctic and French research ship L’Atalante were all steaming at full speed to join the hunt before dawn.
The L’Atalante carries the robot Victor 6000, which is capable of reaching depths of 20,000ft.
A US Navy CURV21 undersea robot was also due to arrive and was seen as the best chance of saving the crew.
The vessel can rescue wreckage and craft up to 20,000ft down and last year pulled off the recovery of a Seahawk helicopter at a depth of 19,075ft off Japan.
However, experts warn that the hunt is a “needle in a haystack” as Titanic's wreck sits about 3,800m (12,500ft) below sea level at the bottom of the ocean.
The victims of the disaster were thought to have been desperately trying to raise help.
GB News understands regular SOS taps were heard and two vehicles, which could only dive to 3000m, both imploded when they attempted to plunge lower.
British billionaire Hamish Harding, who runs an aviation company, is among those missing along with Paul-Henry Nargeolet, a former French Navy diver and Stockton Rush, the chief executive of OceanGate.
Canadian Coast Guard Ship (CCGS) Terry Fox preparing to depart in support of the search for the missing OceanGate Expeditions submersible
Reuters
British businessman Shahzada Dawood, a member of one of Pakistan's richest families, and his 19-year-old son Suleman Dawood are also onboard the vessel.
The OceanGate Expeditions tour group, which takes explorers to the depths of the Atlantic for $250,000 per person, is believed to have lost contact when the vessel was directly above the Titanic wreck.
US Coast Guard Captain Jamie Frederick said the searches have found negative results so far.
He said: "The noises were heard yesterday and this morning, experts are analysing the data but at the moment it is inconclusive.
"We need to have hope... what I can tell you is we are searching in the right area. We have to remain optimistic and hopeful when we are in a search-and-rescue case.”
