A deep-ocean historian and shipwreck analyst who dived with James Cameron for the Titanic has issued a chilling warning about the tourist submersible which has gone missing in the Atlantic.
Parks Stephenson worked as a technical advisor to James Cameron for Titanic, carrying out extensive interior exploration inside the wreck. He first dived the Titanic wreck with director James Cameron in 2005, and has been to the wreck site five times since then and twice to the wreck of the Titanic's sister ship, Britannic.
After a submersible used to take tourists to view the wreck of the Titanic went missing the Atlantic Ocean, he issued a stark warning about the severity of the loss of communication.
Taking to his Facebook page, he said: "No matter what you may read in the coming hours, all that is truly known at this time is that communications with the submersible have been lost and that is unusual enough to warrant the most serious consideration.
"I am most concerned about the souls aboard, whose identifies have not yet been made public."
Speaking on Radio 4's PM programme, Stephenson - who is not directly affiliated with the vessel's operating company OceanGate Expeditions - says each submersible has different characteristics - and described the missing vessel as a "highly unusual event".
He added that they typically take around two hours to reach the depth at which the Titanic lies - and will take around the same time to come back up.
The Boston Coastguard confirmed that a search and rescue operation is underway off the coast of Newfoundland for the submersible. It's not entirely clear how many people were on board when it lost communication, though it's believed there were five people aboard..
Paying tourists can take trips to see the sunken wreck of the Titanic around 370 miles off the coast of Newfoundland, Canada, in small submarines. OceanGate Expeditions is a private company which organises deep sea expeditions, and has confirmed in a statement it owned the missing submersible.
In a statement, they said: "We are exploring and mobilising all options to bring the crew back safely. Our entire focus is on the crewmembers in the submersible and their families.
"We are deeply thankful for the extensive assistance we have received from several government agencies and deep sea companies in our efforts to reestablish contact with the submersible. We are working toward the safe return of the crewmembers."
The company charges $250,000 (£195,270) per person on its eigh-day expedition to the site of the famous wreck, which lies around 3,800m below the ocean surface.
After its discovery in 1985, the wreck has been explored extensively by both divers and submarine crews. The ship now lies in two parts, with the bow and stern separated by around 800m, and a huge field of debris around the vessel.
The trip on OceanGate Expeditions' carbon-fibre submersible is described as a "chance to step outside of everyday life and discover something truly extraordinary."
The submersible can seat five people, according to the company, including a pilot, three paying guests and a "content expert." The dive to the wreck, including descent and ascent, takes around eight hours in total.
