The porthole windows on deep submersibles are conical plugs. They don't break. Either a seal leaked or the carbon fiber failed.

Maybe on competently assembled subs. All bets are off on this one.

Probably was the porthole. It looks like the view port was rated for 1,300 meters. (They were descending to 4,000 meters) An engineer even warned them of the issue, and was fired. I suppose they didn't want to spend the money to develop an adequate one.

Just how instant is that death? Do you die from quickly drowning in the water or is the water pressure enough to also crush your skull to make sure you die without having the chance to feel anything?

Guillotined people can still be alive and feel about 30 second safter their head has been removed from their body.

The pressure at that depth is something like 5000 psi. You're literally dead before your brain has time to comprehend what's happening.

not if the leak leaked for an extended period without ripping open ... then pressure would build up very slowly.

You should read up down the properties of carbon fiber

Water pressure crushes you faster than signals can run from your nerves to your brain.

I have been in a car accident that, in the instant of impact, felt indistinguishable from an explosion, too fast to process anything. I imagine the massive pressure change would cause near-instant incapacitation if not death.

i would expect the impact of the water rushing in that quickly to knock everyone out.

Instant.

Imagine a Ford F150 sitting on every square inch of your body.

It's actually easier to imagine water than trucks

Maybe not for Americans. Actually, converting units to "inches" and "F-150s" is probably the most USA-friendly framing possible.

Is that with Imperial cup holders or metric cup holders ?

Lungs collapse instantly

Both the water pressure, and the submarine material around you. It'd be more akin to your entire body would nearly instantly be squished in all 3 dimensions, with non-compressible items (bulk-head/steel) also inhabiting the same space.

I reckon its instant death. If the sub imploded or the carbon fibre hull failed, then it means large amounts of debris come rushing to you very quickly.

I don't think there will be any bodies to recover.

> Do you die from quickly drowning in the water

logically not in this case. at that point where the water level is sufficient to make someone drown the remaining air would be compressed to several hundred atmospheres pressure.

Who told you that about the guillotine? They'd have zero blood pressure, how do you imagine they'd be conscious?

Iirc they did tests where people agreed to blink a certain number of times etc.

Strange, they never asked those condemned to actually utter some sound or mimic something, isn't it? Well, that's because residual muscle twitch is not controlled and is not conscious. Rapid drop of blood pressure renders the person (well, their head, in that case) unconscious within a couple seconds and it is downhill from there.

> Well, that's because residual muscle twitch is not controlled and is not conscious

And because making sounds without lungs attached to your throat is kinda hard

It would be more like dying from a shockwave from a massive explosives blast. You're going to turn entirely to jelly. Within a few ms there will be nothing left working properly.

I did read somewhere (I don't remember exactly where) that when there is an implosion at great depth the air in the submarine is compressed so quickly that anything flammable (specifically human bodies, plastics, etc) would burn up instantly. So it's a bit like the explosion of the fuel-air mixture in a diesel engine.

Makes sense.

https://en.m.wikipedia.org/wiki/Fire_piston

>Just how instant is that death?

Similar to the Arbogast in The Expanse, but even greater disassembly.