The U.S. Coast Guard is searching for a missing Titanic submersible responsible for transporting tourists to sites of the historic ship’s wreckage, according to reports.

Lt. Jordan Hart of the Boston Coast Guard said personnel were “currently undergoing a search and rescue operation,” according to CBS News. 

It is not yet clear how many people are aboard the submersible.

The excursion is hosted by OceanGate Expeditions, which operates manned underwater trips to the Titanic ruins, which lie about 400 miles off the coast of Newfoundland.

“We are exploring and mobilising all options to bring the crew back safely,” OceanGate said in a statement to BBC News. “Our entire focus is on the crewmembers in the submersible and their families.” 

SEE MORE: Digital scan of Titanic shipwreck reveals never-before-seen details

When the company first launched its expeditions in 2021, it said a host of archaeologists and marine biologists would travel to the wreckage for research and monitoring of the deterioration, according to the Associated Press. But it also invited paid tourists on to help take turns operating sonar equipment and performing other tasks, AP said. 

Ship tracking company MarineTraffic said in a tweet that it observed tugboats headed in the vicinity of the Titanic. “[Three] tugs seem headed to site of Titanic wreck, where a small submersible that takes paying tourists to view wreck has gone missing,” MarineTraffic tweeted

Scripps News has reached out to OceanGate Expeditions and the Coast Guard of Boston for more information. 

The Titanic sank on April 15, 1912, after hitting an iceberg in the North Atlantic Ocean. Some scientists worry the legendary ship won’t be around much longer as its deterioration is speeding up.

SEE MORE: As scientists debate the future of the Titanic, the ocean is eating it

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