PARIS - French oceanographer Paul-Henri Nargeolet, one of the five people on board a submersible missing in the North Atlantic, is a world-renowned expert with more than 35 dives to the Titanic shipwreck under his belt, his colleagues said on Wednesday.

“He is the world specialist on the Titanic, its conception, the shipwreck, he has dived in four corners of the world – he is a superhero for us in France,” said Mr Mathieu Johann, his editor at Harper Collins.

Mr Johann convinced Mr Nargeolet to write his book, In The Depths Of The Titanic, because he said his kids were super fans.

Mr Nargeolet, 77, went missing on Sunday along with four others on a tourist visit aboard the Titan submersible to see the wreck of the British ocean liner, which sank when it hit an iceberg on its maiden voyage in 1912 and now lies on the seabed at a depth of around 3,800m.

A huge search and rescue operation is under way.

The underwater explorer needed convincing to write a book, Mr Johann said, because he wanted to spend all of his time diving.

“He wakes up in the morning, and he wants to go to the sea,” said Mr Johann.

Career in French Navy

Director of underwater research for RMS Titanic, which owns the rights to the ship’s remains, Mr Nargeolet started researching and exploring the Titanic wreck when he joined the French ocean research institute Ifremer in 1986, after a 22-year career in the French navy.

“He piloted the Nautile (a submersible that went to the wreckage). He is known for his great experience… someone that is part of Ifremer history is aboard,” said Mr Olivier Lefort, oceanographic fleet operations director for the institute.

During his explorations of the wreck of the Titanic he brought about 5,500 objects to the surface, including personal items belonging to passengers, like binoculars and letters, said Mr Johann.

He said the only part of the ship that the diver had not explored to date was the safe room, where gold and jewellery would have been kept.

The 1997 film Titanic directed by Mr James Cameron, a friend of Mr Nargeolet, was inspired by images taken by the French explorer, who was amazed by the quality of the reconstructions in the film, shot in a pool, Mr Johann said.

Mr Nargeolet’s French wife Anne lives in Connecticut, and his children live outside of France.

Mr Nargeolet was previously married to American journalist Michele Marsh, who died in 2017. They met after Ms Marsh contacted the explorer to ask for the contact of a Frenchman who had survived the Titanic.

The president of RMS Titanic, Ms Jessica Sanders, said in a statement on Wednesday that Mr Nargeolet’s experience was unparalleled and “no-one has a better chance of navigating equipment failures than he does”.

Mr Bernard Cauvin, director of La Cite de la Mer nautical museum in Cherbourg, who has known Mr Nargeolet since 2009, said: “He is someone extremely humble, and very serene, he was sure of himself but he was rigorous – he wouldn’t have gone somewhere if he was unsure.”