Submarine exploring Titanic wreck missing, search underway

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

OceanGate Expeditions said in a brief statement on Monday that it was "mobilizing all options" to rescue those on board the vessel.

The U.S. Coast Guard did not immediately respond to requests for comment. Media reports said the Coast Guard had launched search-and-rescue operations.

It was not immediately clear how many people were missing.

The family of British billionaire Hamish Harding said he was onboard. His stepson wrote on Facebook that Harding had "gone missing on submarine" and asked for "thoughts and prayers." The stepson subsequently removed the post, citing respect for the family's privacy.

Harding himself had posted on Facebook a day earlier that he would be aboard the sub. There have been no posts from him since.

In a statement, OceanGate 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."

The company is currently operating its fifth Titanic "mission" of 2023, according to its website, which had been scheduled to start last week and finish on Thursday.

The expedition, which costs $250,000 per person, starts in St. John's, Newfoundland, before heading out approximately 400 miles (640 km) into the Atlantic to the wreckage site, according to OceanGate's website.

In order to visit the wreck, passengers climb inside Titan, the five-person submersible, which takes about two hours to descend to the Titanic.

The British passenger ship famously sank in 1912 on its maiden voyage after striking an iceberg, killing more than 1,500 people. The story has been immortalized in nonfiction and fiction books as well as the 1997 blockbuster movie "Titanic."