Rescuers are expanding their search into deeper waters as they hunt for a submersible that went missing near the wreck of the Titanic.

The US Coast Guard and other search and rescue crews have swarmed a remote area in the Atlantic in search for the vessel, called Titan, which went missing on Sunday with five people on board.

Coast Guard Rear Admiral John Mauger told CNN: “As we continue on with this search … we’ve been working through the night with a broad group of partners to bring all capabilities to bear looking on both the surface and now expanding to a subsurface in the area.”

NATO rescue vessel cannot reach required depths – missing Titanic sub latest

Rescuers face a race against time to find the missing submersible as its oxygen supply dwindles.

It is understood from the vessel’s operator, OceanGate Expeditions, Titan had a 96-hour oxygen supply in case of emergencies – meaning the people on board have around two days of “life support” left.

The five people on board are British billionaire Hamish Harding, Pakistani businessman Shahzada Dawood and his son Suleman, chief executive and founder of OceanGate Expeditions Stockton Rush, and French submersible pilot Paul-Henri Nargeolet.

Read more:
What we know about missing Titanic sub
Why the hunt for the missing vessel is so difficult

A major search and rescue operation is taking place some 435 miles south of Newfoundland, Canada, involving the US Coast Guard as well as Canadian and US aircraft.

The Canadian research icebreaker Polar Prince, which was supporting the Titan, reportedly lost contact with the vessel about an hour and 45 minutes after it submerged.

The wreckage of the Titanic that sank in 1912 after hitting an iceberg lies at about 12,500 feet (3,810 metres).

The Titan submersible usually takes two hours to descend to the wreck.

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Missing sub: Timelapse shows marine traffic

Could the Titan have moved close to the surface?

But it was still unclear whether the vessel had resurfaced – or how close to the surface it might have got.

It could have got entangled in the Titanic wreak, it could have sunk deeper, or it could float eventually to the surface.

If the sub got into trouble and warning alerts were triggered, emergency measures should have been implemented to bring the submersible to the surface, Sky News understands.

These would have included dropping weights to bring the sub slowly to the surface.

It is unknown if there was an automatic system on board or when systems would automatically trigger the release.

Additionally measures including adding air to ballast tanks would also have helped bring the submersible to the surface.

In a worst-case scenario, if the sub’s pressure hull imploded, there would have been no survivors.