What is it like in a submarine?

Answer 1

It depends on the boat, but cramped is the best operational word for it. Even in the passageways there's not enough room for 2 people to walk side-by-side; you need to turn sideways to get by each other.

Aside from the occasional change in depth with angles, or high speed turns, you don't even really notice any movement when you're submerged like you would on a surface ship. It's essentially like being in a closed room or building, with no windows or frame of reference for time (e.g., daylight), for days, weeks, or months as the mission requires. The only way you really know what time of day it is is by what meal is being served.

Daily life is pretty structured; standard underway watches unless there's something special happening requiring target tracking or battlestations, training, qualifications, more training, more qualifications. Occasional movies, and once in a great while you actually get to sleep (but not often).