Remains of the Titan submersible have been discovered on the ocean floor, following the fatal implosion of the vessel that instantly killed its passengers.
The submarine was set to explore the famous Titanic wreckage, which is located 12,500 feet beneath the ocean's surface - but now, presumed human remains are said to have been found by the US Coast Guard.
Photos have since emerged online of debris being retrieved from the ocean, and put ashore in St John's, Newfoundland, Canada. These photos have sparked confusion about whether there could be such large pieces of the submersible, despite its 'catastrophic implosion'.
Three Britons were on board - Hamish Harding, Shahzada and Suleman Dawood - as well as OceanGate's American founder Stockton Rush and French deep sea explorer Paul-Henri Nargeolet.
Pieces of the submarine that were retrieved included a large, white section of curved metal - that looks to be the casing of the Titan sub, reports the Mirror.
Another retrieved section showed pieces of cable, onboard computers and other mechanical parts. A large circular part of the Titan, which appeared to be the dome-shaped front section, was also found.
However, many people are still asking the question - how come such large pieces of the submarine have been found, despite a 'catastrophic implosion'?
Read on below for an expert's explanation.
How are there remains of the Titan sub?
Experts have previously explained to NBC News that the water pressure on the submarine would have been the equivalent of the Eiffel Tower - a 10,000 tonne wrought-iron object.
It was reported that the force of the implosion would have been so strong that the submarine's carbon-fiber hull would have just "suddenly vanished" - vaporising and killing everyone inside before they knew what was going on.
A coastguard source from St John's where the ill-fated adventurers set off on June 16 told the Mirror that this debris will be pieced together in order to help with ongoing investigations, including a probe by the UK Marine Accident Investigation Branch.
This inquiry will be made easier due to the size of the remains, according to an expert - but how are there remains to recover?
It has been said that the titanium components of the submarine were able to withstand the strength of the implosion - whereas the carbon fibre parts are more likely to have been vaporised into tiny pieces.
The construction of the submarine included at least one titanium end cap, a ring, and a carbon fibre cylinder.
The sub parts that could have 'disintegrated'
OceanGate had been previously warned by ex-staff members of the safety of the submersible after it was revealed that the carbon fibre hull isn't suitable for deep sea dives.
The hull was the submarine's "Achilles heel" - and it was the part that housed the five tragic passengers.
Tom Maddox, CEO at Underwater Investigators, has confirmed that the investigators expected the Titan to have been shot to pieces during the implosion.
Speaking to the Mail Online, Tom said: "Many of us suspected that, in the case of this catastrophic failure, this implosion, that a lot of the parts would be disintegrated, particularly the non-titanium parts, which, of course, would make the investigation a lot harder to do."
He said that finding bigger pieces means that those looking into this tragic event, "more pieces of the puzzle to put together".
Tom continued: "They'll put it back as best they can. I don't think there's a rulebook for this, you know, there's no manual, this is something new. And they're going to have to kind of write the book as they go along, would be my thought, but they'll use their past experiences and their knowledge to do that."
The physics of the implosion
Meanwhile a university professor of physics at Northeastern, Arun Bansil, has explored a basic map of the physics involved in the violent implosion.
Speaking to Northeastern Global News, Arun said: "In an explosion, the force acts outwards, but in an implosion, the force acts inwards.
"When a submersible is deep in the ocean it experiences the force on its surface due to water pressure. When this force becomes larger than the force hull can withstand, the vessel implodes violently.
"The key is the design of the hull that protects the vessel against the large external water pressure that is trying to crush the hull."
Professor Bansil noted that most of the existing technology is based on titanium, steel and aluminium - as the performance of these materials under pressure is well-understood.
He added: "However, the Titan's hull had an experimental design. It used mostly carbon fibres, which have the advantage of being lighter than titanium or steel, so Titan could have more space for passengers.
"Properties of carbon fibres for deep sea applications are, however, not that well understood. It can crack and break suddenly.
"Titan had previously gone for deep sea dives a few times, which would have contributed to the fatigue of the hull to make the hull more prone to catastrophic failure."
What happens now?
Officials are not sure at this stage how soon into the dive the vessel imploded.
The submarine lost contact with the tour operator, OceanGate Expeditions, an hour and 45 minutes into their two-hour descent towards the wreckage.
The vessel was then reported missing eight hours after communication was lost with the captain.
Stockton Rush, CEO of OceanGate, previously explained in a haunting interview that "as you're descending, you've got your depth and altitude… that's pretty critical. When you get close to the bottom, you have to be ready to drop some weight so you don't go crashing into it, or thrust."
The billionaire, who has now been officially declared deceased, continued at the time: "So getting that notification 200 metres above the bottom is pretty critical.
"And then when we use our laser scanning system, we need correction data for through water speed currents and the light to keep the errors down, and that’s it, that’s the element of adding [coms] on the sub."
Pelagic Research Services – whose remote operating vehicle (ROV) discovered the debris – said on Wednesday its team is 'still on mission'.
In a statement, Captain Jason Neubauer, Chair of the Marine Board of Investigation said: "I am grateful for the coordinated international and interagency support to recover and preserve this vital evidence at extreme offshore distances and depths.
"The evidence will provide investigators from several international jurisdictions with critical insights into the cause of this tragedy.
"There is still a substantial amount of work to be done to understand the factors that led to the catastrophic loss of the Titan and help ensure a similar tragedy does not occur again."
In a statement last week, OceanGate said it was "an extremely sad time for our employees who are exhausted and grieving deeply over this loss"
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