In the "Deepsea Challenge" documentary (2014), Don Walsh (one of the two men that made the dive with Trieste) tells James Cameron that "if you can hear a crack it means you're still alive, might as well keep on with the dive" (paraphrasing). So when Cameron is doing a test dive he hears a loud noise and indeed just keeps going. Personally, I'd wet my pants right there and cry for my mother. These gentlemen are built different I guess.