There have been reports of "banging" noises being detected during the search for a missing submersible.
The deep-sea vessel, which was near the wreck of the Titanic, lost communication with tour operators on Sunday. It was around 435 miles south of St John’s, Newfoundland, during a voyage down to visit the shipwreck off the coast of Canada.
On board Titan were five people who now face a dwindling supply of oxygen, with the US Coast Guard estimating on Tuesday that the 6.7 metres (22ft) long OceanGate Expeditions vessel had just 40 hours left. One of the people on board is British billionaire adventurer Hamish Harding.
