[fergbrain]

The door can still be designed to open outward and also able to be unlatched from the inside: those aren’t mutually exclusive properties.

[stickfigure]

It needs to remain perfectly watertight at over 5000psi or everyone dies. That design constraint probably eliminates most clever latch designs.

[Miraste]

This is usually done with a plug hatch and it's not that complex. The Alvin submersible has one and it's from 1964.

[numpad0]

I was imagining a round door in the middle of the hull, like a submarine hatch, but it looks like the entire front dome comes off and that’s the “hatch”. If so, can’t they just make the front a giant screw and add handles to both sides?