The first British man to dive the Titanic described the site as a “hostile environment with no means of escape.”
Dik Barton has made 22 dives of the wreck and has an in-depth knowledge of the marine environment around it.
Rescue teams are trying to find a submersible tourist vessel which went missing during a voyage to the site of the shipwreck, off the coast of Canada.
Private plane firm Action Aviation said its British chairman Hamish Harding is one of the mission specialists on the five-person OceanGate Expeditions vessel, which is 6.7 metres long (22ft).
UK-based businessman Shahzada Dawood and his son Sulaiman have also been named in a family statement as two of the other people on board the craft.
The submersible, named Titan, lost communication with tour operators on Sunday while about 435 miles south of St John’s, Newfoundland.
Mr Barton, who is a guest lecturer at the University of Sunderland, said: “This is incredibly sad news, and in light of recent events, sadly the Titanic exploration community always anticipated that this would be the case.
“The vessel is not designed to survive those depths for this duration, time sadly is running out. This is a hostile environment with no means of escape.”
The former Army officer, from Cumbria, was the first Briton to dive to the wreck during his time as vice president (operations) with RMS Titanic, Inc.
He managed the Titanic Artefact Collection, which includes more than 6,500 recovered artefacts.
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