many ways, 20th century was very good for submarines. They went into it little more than under-armed curiosities unable to
remain submerged for more than a few hours, couldn't move more than a
short distance from base and were condemned as "underhand, unfair, and
damned Un-English." They came out as the most powerful
warships on Earth; capable of operating beneath the sea for as long as
the food held out, not needing to be refuelled for years, moving at
speeds usually associated with the Blue Riband, and able to spot the
bull with a missile half a world away.
But that's not good enough. We still don't have anything like
the updated Nautilus of the sort pictured above with its atomic
engines sucking in water and the odd halibut at the bow only to blast
them out as an incandescent jet from the stern.
Which no doubt is some relief to the halibut.