The US Coast Guard will lead an international investigation into the loss of the Titan submersible that was carrying five people to the Titanic, to determine what caused it to implode.

Captain Jason Neubauer, chief investigator, said the salvage operations from the sea floor are ongoing, and they have mapped the accident site. The convening of a Marine Board of Investigation is the highest level of investigation conducted by the US Coast Guard, Neubauer said.

The Coast Guard board can make recommendations to prosecutors to pursue civil or criminal sanctions as necessary.

Investigators are working closely with other national and international authorities, including the Transportation Safety Board of Canada, the French marine casualties investigation board and the United Kingdom Marine Accident Investigation Branch. Evidence is being collected in the port of St. John’s, Newfoundland, in coordination with Canadian authorities.

“My primary goal is to prevent a similar occurrence by making the necessary recommendations to advance the safety of the maritime domain worldwide,” Neubauer said.

The Titan’s mother-ship, the Polar Prince left Newfoundland on June 16, towing the ill-fated submersible.

The Titan imploded on its way to tour the Titanic wreckage, killing all five on board. Debris was located about 3,810 metres underwater, and roughly 488 metres from the Titanic.

OceanGate Expeditions, the company that owned and operated the Titan, is based in the US but the submersible was registered in the Bahamas. The Polar Prince, was from Canada, and those killed were from England, Pakistan, France, and the US

The Titan was not registered as a US vessel or with international agencies that regulate safety. And it wasn’t classified by a maritime industry group that sets standards on matters such as hull construction.

Questions about the submersible’s safety were raised by both by a former company employee and former passengers.

However, OceanGate CEO Stockton Rush, who was piloting the Titan when it imploded, had complained that regulations can stifle progress.

Killed in the implosion were Rush; two members of a prominent Pakistani family, Shahzada Dawood and his son Suleman Dawood; British adventurer Hamish Harding; and Titanic expert Paul-Henri Nargeolet.

– AAP