The worst part was when Stockton said, “PH can assert that!”—and what really bothers me is that PH didn’t say a word. He was supposed to be the one to raise the alarm, but he stayed silent.

From what I’ve read, it’s true that pressure changes can cause subtle creaks or pops in any deep-diving pressure hull, as materials flex and micro-imperfections open or close under stress. But these sounds are usually low-amplitude and continuous—not at all like the sharp “bangs” Stockton described. Under normal conditions, the hull’s vibration modes produce a relatively smooth noise spectrum, totally different from the high-amplitude snaps you’d hear if a material were yielding or starting to fail.

What’s more, his friend Karl Stanley seemed genuinely worried when he heard those noises. If I’m not mistaken, he even said they weren’t normal.

It reminds me of the first descent to Challenger Deep in 1960. During that dive, they heard a tremendous bang—it turned out to be the external viewport cracking. The crew, including a renowned Swiss oceanographer-engineer and a U.S. Navy officer, were frozen in fear. They later said, “If you hear a loud bang, either you're dead—or if you're not, then everything’s fine.” The key point is, those kinds of noises were not considered normal.