A rescue operation was underway deep in the waters of the Atlantic Ocean in search of a submarine that carries people to view the wreckage of the Titanic.

The Joint Rescue Coordination Centre in Halifax, Nova Scotia said the vessel was reported overdue around 9:13 p.m. Sunday, about 435 miles (700 kilometres) south of St. John’s, Newfoundland. Lt. Cmdr. Len Hickey said a Canadian Coast Guard vessel and military aircraft were assisting the search effort, which was being led by the U.S. Coast Guard in Boston.

OceanGate Expeditions confirmed the search for its five-person submersible and said its focus was on those aboard the vessel and their families.

“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,” the company said in a statement. “We are working toward the safe return of the crewmembers.”

In 2021, OceanGate Expeditions began what it expected to become an annual voyage to chronicle the deterioration of the iconic ocean liner that struck an iceberg and sank in 1912, killing all but about 700 of the roughly 2,200 passengers and crew. Since the wreckage’s discovery in 1985, it has been slowly succumbing to metal-eating bacteria, and some have predicted the ship could vanish in a matter of decades as holes yawn in the hull and sections disintegrate.

In describing its first expedition, OceanGate said that in addition to archaeologists and marine biologists, the expeditions also would include roughly 40 paid tourists who would take turns operating sonar equipment and performing other tasks in the five-person submersible.

The initial group of tourists was funding the expedition by spending anywhere from $100,000 to $150,000 apiece.

(AP)