A massive search and rescue effort is under way in the North Atlantic after a submarine exploring the wreck of the Titanic went missing on Sunday.
The research vessel Polar Prince lost contact with the Titan submersible an hour and 45 minutes into its dive.
It is believed there are five people on board the submarine, including Hamish Harding, a 59-year-old British billionaire businessman and explorer.
The US Coast Guard estimates the sub has between 70 and 96 hours of emergency oxygen.