Every theory about what happened to the missing Titanic sub, unpacked by experts 

The US Coast Guard has confirmed the missing Titanic submarine with five people on board will run out of oxygen by 11am on Thursday. And, as the rescue and search mission rushes to find the vessel, which is lost somewhere in the mid-Atlantic ocean, multiple theories have been emerging on what actually happened to the horrifyingly claustrophobic ship millionaires risk their lives to climb on board.

So, in case you’re curious (aren’t we all) about what the most up to date theories about the missing Titanic submarine are, here are the top three hypothesis, fact checked by John Carlton, Professor of Marine Engineering at City, University London.

The submarine is floating on the surface of the water

One theory that came up early on in the search for the missing Titanic submarine is that the vessel is floating on the surface of the ocean after some kind of electrical failure or other tech problem. But the Coast Guard have been searching and are yet to spot the submarine, so this could be unlikely.

And, even if the vessel has returned to the ocean’s surface, the passengers wouldn’t be able to get out as the doors are locked from the outside. So, they’d still be running out of oxygen. Pure horror film energy.

Professor Carlton’s verdict: “This is a possibility but surveillance is extremely good from military aircraft and satellites in the North Atlantic. However, the vessel is small (6.7m in length) and it might possibly be overlooked particularly if there is any kind of sea running.  Probably unlikely though because military surveillance is of a very high order.”

The vessel has imploded under water pressure

Another running theory from multiple experts about the Titanic submarine is that it imploded under the deep water pressure, which could explain the ship totally losing all radio communication. If the ship imploded, the impact would be horrific and there’d likely be no large pieces of debris for the Coast Guard to find.

Professor Carlton’s verdict: “Faint knocking noises [presumably made by survivors] have been reported by one of the search authorities. In submarine crashes this has also been reported in similar circumstances when there is still life on-board [if the ship had imploded, there would be no survivors].”

They’re stuck inside the Titanic shipwreck

The missing submarine, which was designed to take millionaires down to look at the Titanic shipwreck could also now be stuck inside the 11-year-old boat’s ruins – 12,500 feat at the bottom of the Atlantic Ocean about 370 miles off the coast of Newfoundland in Canada.

If that’s the case, the submarine could be really hard to find because the Coast Guard has said there’s a lot of debris down there. Additionally, they might have to damage the Titanic shipwreck in order to get them out.

Professor Carlton’s verdict: “This is a possibility but the submersible was piloted by an experience navigator. Although, conditions are difficult at 3.8km below the surface.

“This begs the question of what else could have gone wrong. Anything at this stage has to be speculation but possibilities could include: Local or electrical failure, seal failures, fatigue – this vessel has dived before (I think 20-25 times), damage when launching from the mother ship.”

Essentially, until more evidence emerges – the answers are unclear.

Related stories recommended by this writer:

• A look inside the horrifyingly claustrophobic missing Titanic submarine 

• Who is Hamish Harding – British Billionaire on board the missing Titanic submarine 

• All the theories about what happened to MH370 plane that mysteriously disappeared