Wikipedia: https://en.wikipedia.org/wiki/DSV_Alvin
Sounds like it was (shocker) really well designed. It even sank once when a cable snapped on support boat — crew escaped, and it was recovered and retrofit. And if things go sideways, the cabin/titanium sphere could detach, floating freely up to the surface.
After hearing about OceanGate, deep sea subs sounded terrifying — but reading about this is somehow very comforting.
Deep sea subs designed by people whose only actual attribute as a person is having money are terrifying.
The one thing I’ve learned in my 35 years of corporate work is that rich people are absolutely not smarter, and definitely not wiser, than the average worker.