[foobar1962]

> Can any engineers comment on whether that task is easier for a vessel exposed to compression (under sea) as opposed to vacuum (space)?

I believe the pressure where the Titanic lays is 300 atmospheres. The pressure differential for the submarine is 300 - 1 = 299 atmospheres.

A vessel in space will be have a pressure differential of 1 atmosphere to contend with.

[wnc3141]

I too am interested in this question, may I piggyback and add a question about whether the basic capsule shape is as efficient in negative pressure as it is in positive pressure

[foobar1962]

The design of pressurised aircraft is probably a good example to study.