Titan sub: How trip to Titanic turned from smiles to tragedy

A place on the sub cost up to $250,000 (£186,000) – and over the course of 2021 and 2022 Titan made 23 dives, 12 of which successfully reached the wreck of the Titanic.

But these descents were far from problem free. A dive log book recorded 118 technical faults, ranging from thrusters failing, to batteries dying – and once the front dome of the sub fell off.

The investigation focused on a dive that took place in 2022, when paying passenger Fred Hagen heard an “alarming” noise as the sub was returning to the surface.

“We were still underwater and there was a large bang or cracking sound,” he said.

“We were all concerned that maybe there was a crack in the hull.”

He said Mr Rush thought the noise was the sub shifting in the metal frame that surrounded it.

The US Coast Guard inquiry was shown new analysis of data from the sub’s sensors, suggesting the noise was caused by a change in the fabric of the hull.

This affected how Titan was able to respond to the pressures of the deep.

Phil Brooks, Oceangate’s former Engineering Director, said the craft wasn’t properly checked after that dive because the company was struggling financially, and instead it was left for months on the dockside in Canada.