A Titanic expert who worked with James Cameron weighed in on the missing submersible

• An explorer who worked with James Cameron on various Titanic-related projects weighed in on the missing submersible.
• Parks Stephenson said the fact that the submersible lost contact with the mother ship was "unusual."

A Titanic expert and explorer who worked with James Cameron on various Titanic-related projects weighed in on the mysterious disappearance of the submersible Titan, which was carrying tourists to explore the wreck of the RMS Titanic.

In a Facebook post on Monday, Parks Stephenson emphasized the gravity of the disappearance of the underwater vehicle.

"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," Stephenson wrote. "I am most concerned about the souls aboard, whose identities have not yet been made public."

He included a link to a BBC story about the submersible's disappearance.

Stephenson worked as an advisor on "Ghosts of the Abyss," Cameron's 2003 documentary about the Titanic wreck, which came out six years after the director's 1997 epic about the doomed ship. Stephenson reportedly first visited the wreckage of the Titanic — which sits over 2 miles below the ocean surface — in 2005 with Cameron and returned numerous times throughout the years, most recently in 2019.

Stephenson offered insight into the wreck when the first full-sized scans of the ship were revealed this year. "There are still questions, basic questions, that need to be answered about the ship," Stephenson told the BBC in May. Stephenson added that it was possible the ship didn't hit the iceberg on the starboard side, something the scans could help determine.

The Titan submersible was reported missing on Sunday and is said to have five people on board. A search-and-rescue mission is underway in the Atlantic Ocean.

Correction: June 20, 2023 — An earlier version of this story mischaracterized Stephenson's work with James Cameron. He did not work on the 1997 film "Titanic," but on Cameron's other Titanic-related projects.