<p>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.</p>.<p>OceanGate Expeditions said in a brief statement on Monday that it was "mobilizing all options" to rescue those on board the vessel. It was not immediately clear how many people were missing.</p>.<p>The U.S. Coast Guard did not immediately respond to requests for comment. Media reports said the Coast Guard has launched search-and-rescue operations.</p>.<p>"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 said in a statement.</p>.<p>The company is currently operating its fifth Titanic "mission" of 2023, according to its website, which was scheduled to start last week and finish on Thursday.</p>.<p>The expedition, which costs $250,000 per person, starts in St. John's, Newfoundland, before heading out approximately 400 miles into the Atlantic to the wreckage site, according to OceanGate's website.</p>.<p>In order to visit the wreck, passengers climb inside Titan, a five-person submersible, which takes about two hours to descend to the Titanic.</p>.<p>The British passenger ship famously sunk in 1912 on its maiden voyage after striking an iceberg, killing more than 1,500 people. The story has been immortalized in non-fiction and fiction books as well as the 1997 blockbuster movie <em>Titanic</em>.</p>
<p>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.</p>.<p>OceanGate Expeditions said in a brief statement on Monday that it was "mobilizing all options" to rescue those on board the vessel. It was not immediately clear how many people were missing.</p>.<p>The U.S. Coast Guard did not immediately respond to requests for comment. Media reports said the Coast Guard has launched search-and-rescue operations.</p>.<p>"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 said in a statement.</p>.<p>The company is currently operating its fifth Titanic "mission" of 2023, according to its website, which was scheduled to start last week and finish on Thursday.</p>.<p>The expedition, which costs $250,000 per person, starts in St. John's, Newfoundland, before heading out approximately 400 miles into the Atlantic to the wreckage site, according to OceanGate's website.</p>.<p>In order to visit the wreck, passengers climb inside Titan, a five-person submersible, which takes about two hours to descend to the Titanic.</p>.<p>The British passenger ship famously sunk in 1912 on its maiden voyage after striking an iceberg, killing more than 1,500 people. The story has been immortalized in non-fiction and fiction books as well as the 1997 blockbuster movie <em>Titanic</em>.</p>