'All good here' : Titan sub crew's last words before implosion

The last words heard from the five-person crew of the Titan submersible were "all good here" before the craft imploded deep in the ocean and killed them, a hearing has revealed.

Investigators with the US Coast Guard said it was among the final communications between the Titan and its mother ship before they lost contact for good.

The deep-sea vessel was en route to the wreck of the Titanic in June 2023 when it imploded less than two hours into its descent.

The US federal agency kicked off a fortnight-long inquiry on Monday that "aims to uncover the facts surrounding the incident and develop recommendations to prevent similar tragedies in the future".

It is the first public phase of a probe that began 15 months ago into an undersea disaster that sparked international search and rescue efforts.

Unanswered questions over the Titan's ill-fated dive have fuelled a lingering debate over safety and regulation in the world of private undersea exploration.

OceanGate, the Washington-state based manufacturer behind the craft, has faced questions over its design choices, its safety record and its adherence to regulations.

As many as 10 former OceanGate employee, including co-founder Guillermo Sohnlein, and experts in marine safety and undersea exploration, are expected to testify over the next two weeks before the Coast Guard's Marine Board of Investigations (MBI).

MBI is the highest available level of inquiry into US marine casualties and convenes roughly one hearing per year, its chairman told reporters on Sunday.

"Out of thousands of investigations conducted, less than one rise to this level,” Jason Neubauer said.

"There are no words to ease the loss endured by the families impacted by this tragic incident," he added.

"But we hope that this hearing will help shed light on the cause of the tragedy and prevent anything like this from happening again."

The board, which is made up of top Coast Guard and National Transportation Safety Board (NTSB) officials, has the authority to recommend civil penalties or make referrals for criminal prosecution by the US Department of Justice.

A sprawling search and rescue mission involving four governments unfolded after the submersible lost contact with its mother ship, the Polar Prince, on the morning of 18 June 2023 and never resurfaced.

On board were OceanGate's founder and CEO Stockton Rush, British explorer Hamish Harding, veteran French diver Paul Henri Nargeolet, the British-Pakistani businessman Shahzada Dawood and his 19-year-old son Suleman.

Debris containing their "presumed human remains" was recovered in ensuing days as authorities concluded Titan had suffered a "catastrophic implosion", collapsing inward under immense pressure.

On Monday, investigators presented an animated recreation of the journey that detailed the repeated text messages between Titan and the Polar Prince.

Support staff aboard the mother ship asked about the submersible's depth and weight, as well as whether it could still see the ship on its onboard display, but the crew's responses grew increasingly spotty, Coast Guard officials said.

Also presented on Monday was a historical overview of the Titan, with officials noting that its hull had never been subject to third-party testing and had been left exposed to weather and other elements while it was in storage for seven months between 2022 and 2023.

OceanGate suspended all exploration and commercial operations following the incident.

The company currently has no full-time staff but is cooperating with investigators and will be represented by an attorney at the MBI hearings, it said in a statement to the Associated Press.

The fortnight of public inquiries in North Charleston, South Carolina will delve into "all aspects of the loss of the Titan", including "pre-accident historical events, regulatory compliance, crewmember duties and qualifications, mechanical and structural systems, emergency response and the submersible industry".

Additional hearings may yet be scheduled in a probe that was initially slated to last about a year.

Once the investigation wraps up, both the Coast Guard and the NTSB will produce reports containing their independent analysis.