A British explorer and businessman is among those on the missing submarine.

Hamish Harding, a British businessman and explorer, was among those aboard the submarine that went missing in the North Atlantic on Sunday, according to Mark Butler, the general manager of Mr Harding’s company, Action Aviation.

Mr Harding, 58, holder of several Guinness World Records, including one for the longest time spent traversing the deepest part of the ocean in a single dive, wrote on his Facebook page on Saturday that he was proud to finally announce that he joins OceanGate’s mission “on the submarine descending to the Titanic.”

Mr. Harding is the Chairman of Action Aviation, a sales and aviation company based in Dubai. He had previously flown to space on a mission for Jeffrey P. Bezos’ Blue Origin rocket company. He also participated in a cheetah reintroduction mission to India, and holds a world record for the fastest circumnavigation of the Earth through both geographic poles by aircraft.

In a Instagram message on Saturday with photos of the submarine and of him signing a flag for the Titanic mission, he wrote that the group had departed from St. Johns, Newfoundland, Canada, on Friday and planned to begin dive operations on Sunday around 4 a.m. to start.

The post included a reference to PH Nargeolet as a member of the underwater team. Paul Henry Nargeolet is a French authority on the Titanic wreck and has made numerous underwater dives to its site.

Despite winter being particularly harsh in Newfoundland this year, “a weather window has just opened,” he added.

“More expedition updates to follow,” he wrote. “WHEN the weather permits!”

On Monday, the president of The Explorers Club, a New York-based organization of which Mr. Harding was a board member, alerted members of the club to the disappearance of the submarine on which Mr. Harding, along with four other people, attempted to reach the Titanic .

“When I saw Hamish at the Global Exploration Summit last week,” wrote the official, Richard Garriott de Cayeux, “His excitement about this expedition was palpable. I know he was looking forward to doing research on the site.

“We all hope that the submarine is located as soon as possible and that the crew is safe.”