Paul-Henri Nargeolet, a French maritime knowledgeable who has been on over 35 dives to the Titanic wreck website, is among the 5 individuals aboard the submersible that has been lacking since Sunday, in keeping with his literary consultant, Mathieu Johann.

Mr. Nargeolet, 77, is the director of underwater analysis for RMS Titanic, Inc., an American firm that owns the salvage rights to the well-known wreck and shows most of the artifacts at Titanic exhibitions. The firm performed eight analysis and restoration expeditions between 1987 and 2010, in keeping with its web site.

The dozens of dives Mr. Nargeolet has made to the wreck website embrace earlier OceanGate expeditions on the Titan, the lacking submersible. In 2022, he enabled the invention of an “extraordinarily biodiverse abyssal ecosystem on a previously unknown basalt formation near the Titanic,” according to the company.

Mr. Nargeolet’s firm, RMS Titanic, didn’t instantly reply to a request for remark. On Sunday, in a statement on Twitter, it expressed “heartfelt support to the Boston Coast Guard during their search and rescue mission” however made no point out of Mr. Nargeolet.

While Mr. Nargeolet was born in Chamonix, within the French Alps, he has devoted his profession to the ocean. He was an beginner diver in his youth earlier than becoming a member of the French Navy in 1964, in keeping with a biography printed on the web site of the Cité de la Mer, an oceanography museum in Cherbourg, France, that has hosted exhibitions of objects salvaged from the wreck and that has collaborated with Mr. Nargeolet.

During 20 years within the Navy, he was a mine-clearing diver, a deep-sea diver, and a submarine pilot. That expertise led him to work for IFREMER, a publicly funded French maritime analysis institute, the place he was in command of its submarine exploration crafts throughout early expeditions to the Titanic wreck. His first dive to the Titanic was in July 1987, about two years after the wreck was found.

“It was a pretty unforgettable moment,” Mr. Nargeolet mentioned in an interview final yr with HarperCollins France, which had simply printed a book he had written in regards to the Titanic.

He described how the small workforce contained in the craft was chatty till it reached the wreck. Then, he mentioned, “for the next 10 minutes there wasn’t a sound in the submarine.”

“We didn’t know at that time that we would return several times, and that I would return as often as I have been able to,” he added.

In the interview, Mr. Nargeolet mentioned the Titanic had captured public creativeness not simply due to James Cameron’s 1997 film however as a result of everybody discovered one thing to latch onto, whether or not the ship’s development, the various passenger checklist, or the sinking itself.

“Once you’ve gotten your head into the Titanic, it’s hard to get it out,” he mentioned.

Mr. Nargeolet was married to Michele Marsh, an Emmy Award-winning newscaster who was a celebrated anchor on nightly packages in New York City for over 20 years. She died in 2017.

Last yr, Mr. Nargeolet told the French newspaper Ouest-France that he met Ms. Marsh after she contacted him to safe an interview with Michel Navratil, a Frenchman who was the considered one of final survivors of the Titanic.

Emma Bubola contributed reporting.