[gs17]

No one is proposing a literal "suicide door". But it makes sense to have it openable after surfacing, at least for emergencies.

[stickfigure]

"Surfacing" unassisted would mean floating with the top of the submarine at water level. You still won't be able to open the door.

[gs17]

That's possible. Then at least some form of ventilation usable after surfacing should have been included if you're locking people in.

[stickfigure]

Every thruhull is a potential source of death at 5000+ psi.

The bigger problem seems like underinvestment in "getting found" technology.

[93po]

There is 96 hours of oxygen onboard, and even without any supplement, 5 people would survive in a space that large for at least half a day with no fresh air