With all the talk about failure modes of carbon fiber, the scariest part of this article is the photo of the display and light held up by screws drilled into the side of the pressure vessel.
Strain monitoring built into the hull only helps you if you can surface in time once you notice a problem, and not at all if it is a catastrophic failure.
Might have been from the Byford Dolphin accident: https://en.wikipedia.org/wiki/Byford_Dolphin
"Hellevik, being exposed to the highest pressure gradient and in the process of moving to secure the inner door, was forced through the crescent-shaped opening measuring 60 centimetres (24 in) long created by the jammed interior trunk door. With the escaping air and pressure, it included bisection of his thoracoabdominal cavity, which resulted in fragmentation of his body, followed by expulsion of all of the internal organs of his chest and abdomen, except the trachea and a section of small intestine, and of the thoracic spine. These were projected some distance, one section being found 10 metres (30 ft) vertically above the exterior pressure door."
I wonder if anyone knows if this universally true? Would the inhabitants of this submarine have experienced a similar fate if one of those bolts failed or a hole in the hull developed?
In the event you could contain it to a simple pinhole and not have it instantly crush, the stream of water would cut anything placed in its path. It would work similar to a lightsaber.
Though as you said, the far more likely outcome is that the vessel would crush almost instantly.
A pressure washer maxes out around 4000 PSI for a powerful one, and that can easily cut through flesh.