A tourist submarine that explores the Titanic wreckage has gone missing with five people on board.
A massive search and rescue operation is now underway after the sub lost contact about an hour and 45 minutes into its dive on Sunday.
Both the US and Canadian Navies are helping with the search and rescue operation.
A ticket on board the OceanGate Titan submarine costs $250,000.
The Titanic submarine takes five people down for each trip and carries enough oxygen for four days.
On Monday afternoon, the US Coast Guard said it anticipated there would be “somewhere between 70 and the full 96 hours available at this point”.
Among those on board was 58-year-old British billionaire Hamish Harding.
Right before the trip, Mr Harding took to social media to say he was “proud to finally announce” that he would be aboard the mission.
“A weather window has just opened up and we are going to attempt a dive tomorrow,” he said.
While no one knows the cause of the sub’s disappearance, experts have offered several possible scenarios.
They suggest the sub might have become tangled in the Titanic wreckage or experienced either a power outage or a failure with the communications system.
The company says the Titan sub is packed with survival equipment so those on board have the best chance at survival in an emergency.
About the OceanGate Titan Sub
The OceanGate submersible usually has five people on board, including a pilot, a content expert, and three paying guests.
Each dive reaches a depth of 3,800m (12,500 ft) and takes about eight hours.
The submersible is 6.7m (22ft) long and weighs more than 10,000kg (23,000 lbs).
It has four electric thrusters and is packed with technology including cameras, lights, and scanners.
The Titan sub also uses Elon Musk’s Starlink satellite technology to communicate.