Bonus round:
According to US officials, poor engineering was the main reason for the disaster.
OceanGate’s Titan submersible imploded on its journey to the wreck of the Titantic because of poor engineering and multiple failures to test the vessel, according to an official report.
Titan imploded in June 2023, killing all five passengers on board including OceanGate’s chief executive.
The US National Transportation Safety Board (NTSB) found the engineering process behind the vehicle was “inadequate”, resulting in faults which meant it failed to meet strength and durability requirements.
https://www.yahoo.com/news/articles/titan-imploded-due-poor-engineering-064925901.html
One interesting piece of info is the chatlog:

they dropped two [weights] shortly before the disaster, and it would be interesting to know if they did it because they wanted to slow down descent, or they wanted to get back up as quickly as possible. My guess that it’s former, and they probably didn’t have much, if any, warning of the impending doom.
They also recovered the intact SD card from a badly damaged underwater camera, but no useful images on it since the camera was set to save into an external device.
https://petapixel.com/2025/10/16/sd-card-recovered-from-camera-that-was-onboard-oceangate-titan-sub/
The hard to understand part here is the redaction request by the manufacturer….
Manley shared official documents from the National Transportation Safety Board, which contain photos of the underwater camera and SD card. However, part of the images are bizarrely redacted at the manufacturer’s request.