A submersible on a tourism expedition to explore the wreckage of the Titanic has gone missing off the coast of southeastern Canada, the private company that operates the vessel said on Monday.

OceanGate Expeditions said in a brief statement issued to the BBC and other media that it had lost contact with the submersible and was “mobilizing all options” to rescue those on board.

The regional branch of the US Coast Guard said that it was seeking a submersible vehicle in the Atlantic Ocean, somewhere around the site of the Titanic shipwreck.

“A US Coast Guard C-130 crew is searching for an overdue Canadian research submarine approximately 900 miles off Cape Cod,” USCG Northeast said.

It said a Canadian plane with underwater detection capabilities was assisting in the search.

“The US Coast Guard is searching for a 21-foot submersible from the Canadian research vessel Polar Prince,” it said a short while later, referring to Ocean Gate Expeditions’ vessel.

“The 5 person crew submerged Sunday morning, and the crew of the Polar Prince lost contact with them approximately 1 hour and 45 minutes into the vessel’s dive,” the Coast Guard said.

“We are deeply thankful for the extensive assistance we have received from several government agencies and deep sea companies in our efforts to reestablish contact with the submersible,” OceanGate Expeditions said.

Additional resources would arrive in the coming days, said Rear Admiral John Mauger, a commander for the US Coast Guard.

“It is a remote area, and it is a challenge to conduct a search in that remote area,” he said. “But we are deploying all available assets to make sure we can locate the craft and rescue the people on board.”

David Concannon, an adviser to OceanGate, said the vessel had a 96-hour oxygen supply starting at roughly 6 a.m. Sunday. He added that officials were working to get a remotely operated vehicle that can reach a depth of 6,000 meters (about 20,000 feet) to the site at the earliest.

Titan sub typically seats five

According to company information, the vessel, named Titan, usually accommodates five people — a captain, an expert on the Titanic wreckage, and three guests, often paying ones. The tour lasts days and costs around $250,000 (around €230,000) per person.

OceanGate also takes archaeologists and other experts to the scene of the ship wreck to track decay at the site.

British billionaire and enthusiast thought to be on board

British businessman Hamish Harding, based in the United Arab Emirates, had written on social media on Sunday that he would be on board the sub.

“I am proud to finally announce that I joined [Ocean Gate Expeditions] for their RMS TITANIC Mission as a mission specialist on the sub going down to the Titanic,” Harding wrote, noting that bad weather had been making it difficult to find windows for the dives.

Harding’s company, Action Aviation, confirmed to the Associated Press that he had been on board.

Harding, who made his fortune in the business aviation sector in the Gulf, is something of an undersea exploration enthusiast. He is in the Guinness Book of World Records three times, with two of the records being the longest distance traveled at full ocean depth and the longest time spent at full ocean depth, both from a 2021 mission.

He and Victor Vescovo took the Challenger Deep two-man submarine to the deepest point of the Mariana Trench in the Western Pacific Ocean. It’s some 36,000 feet (almost 11,000 meters) below sea level. By comparison, Mount Everest’s summit is less than 9,000 meters above sea level.

The British-built Titanic, billed as the new benchmark in luxury cruising when it was built, famously sunk on its maiden voyage to the US in 1912 after hitting an iceberg.

The tale has been immortalized in several non-fiction and fiction books as well as the blockbuster film “Titanic” from 1997.

msh/rs (AFP, AP, Reuters)