vessel

The vessel suffered a catastrophic failure as it neared the sea floor, killing all five people onboard.

The sub’s hull was also made out of carbon fibre, an unconventional material for a deep-sea vessel.

Rory Golden, who was on the Oceangate expedition when contact was lost, recently told the BBC those on board the surface vessel experienced four days of fear and “false hope”.

The assessment would have confirmed whether the vessel - from its design through to construction, testing and operations - met certain standards.

The vessel also had an acoustic monitoring device - essentially mics fixed to the sub listening for signs it was buckling or breaking.