A crewed submersible has gone missing with five people onboard on an expedition to view the wreckage of the Titanic (Picture: AP/PA)

The five people on the submersible missing on a dive to the Titanic will face ‘sheer panic’ and claustrophobia, an oceanographer has said.

Hope that they are still alive was provided this morning after a search aircraft detected ‘underwater noises’ as it tried to locate the mini-sub.

The OceanGate Expeditions vessel has been missing since Sunday after setting off to the wreck, which lies 3,800 metres under the Atlantic Ocean.

The 22ft-long Titan sub is thought to have around 24 hours of emergency oxygen left onboard — which would run out at around 11am tomorrow.

Oceanographer Dr Simon Boxall, of the University of Southampton, said: ‘The big issue the search and rescue teams have is that the submersible is most likely in deep water, around four kilometres down.

‘It’s a very difficult environment to work in and there are very few vehicles or systems that can work at that depth. The first job of course is to identify exactly where the submersible is and if it is intact. It is a slow-moving vehicle and we know where the currents are in that area so being able to track where it is likely to be shouldn’t be too difficult.

MORE : For the latest news on the Titanic sub search, follow Metro.co.uk’s live blog here

The OceanGate Expeditions submersible vessel named Titan used to visit the wreckage site of the Titanic (Picture: American Photo Archive/Alamy/PA Wire)

‘The problem is there is only a short period of time to search because of the limited oxygen supply onboard the submersible.

‘They only have enough oxygen to last them through to Thursday, according to the people who own the submarine.’

‘Life for the people onboard will be pretty miserable.

‘Quite apart from the sheer panic of being stuck it will be very cramped as the submersible was only designed for a few hours’ use at any one time.

‘It’s pretty much just a tube with very little inside, it’s not what you would call comfortable.’

British billionaire explorer Hamish Harding and renowned French diver Paul-Henry Nargeolet are among those on the Titan.

British businessman Shahzada Dawood, 48, who is from one of Pakistan’s most wealthy families, and his son Suleman, 19, and experienced engineer Stockton Rush, OceanGate’s chief executive, are also onboard.

‘They will be holding tight and hoping that the submarine is discovered and there is some kind of rescue attempt,’ Dr Boxall said.

‘They might have taken some water down with them but the oxygen supply will be a more immediate concern than water or food.

‘A lot of people are saying why don’t they have escape hatches, but you can’t escape at that depth, if you went outside the phenomenal water pressure would mean you would be crushed within a second.

‘There is no way of telling at this moment in time why they haven’t come back to the surface. If they had of come back up they would likely have been frantically contacting the mothership and using radio to call for help.

‘Sadly, I think this scenario is highly unlikely.’

The submersible vessel which had been visiting the wreckage site of the Titanic (Picture OceanGate Expeditions/PA)

The Titan lost contact with its mothership, the Canadian research icebreaker MV Polar Prince, an hour and 45 minutes after submerging on Sunday morning. The sub had been headed to the shipwreck, which lies around 370 miles off the coast of Newfoundland, Canada.

At least five vessels are now at the wreck site as part of the major search and rescue effort led by the US Coast Guard across an area of 7,6000 square miles. Hope was provided when a Canadian P-3 aircraft detected ‘underwater noises’ in the search area.

Captain David Marquet, a former US submarine commander, speculated that the five could be taking turns to try and alert rescuers.

He told the Mirror: ‘They might have one person banging on the hull to make noise and have the other four people on board sleeping.

‘Then taking turns doing that.’

A picture taken by OceanGate Expeditions showing an interior view of their submersible vessel (Picture: PA, file image)

However, Dr Boxall, of the School of Ocean and Earth Science, warned that a rescue will still be a gargantuan task if and when the sub is located.

‘We have to remember that it took us decades to discover the Titanic, and you have to consider the size of the wreck and the fact they knew roughly where that went down,’ he said.

‘On the assumption that the sub is stranded at a depth of four kilometers, the next issue is how they recover it once they’ve located it.

Another view of the Titan submersible shows the vessel launching from a platform (Picture: Handout/OceanGate Expeditions/AFP via Getty Images)

‘This would be a phenomenally big task even if it was planned months in advance. It’s not like on land where you can pick up a phone and get specialist rescue equipment to you in a few hours, these things take much longer in a remote part of the Atlantic Ocean.

‘Those onboard will be incredibly fortuitous and lucky if the submersible is found and recovered in the time period left. This will need one of the most incredible rescue efforts the world has ever known.

‘All we can do is wait and hope.’

MORE : Great-granddaughter of Titanic engineer gives her verdict on tourist expeditions to ‘ocean graveyard’

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The five onboard the lost deep sea submersible face ‘sheer panic’ and claustrophobia in fight to survive.