[sgarland]

> Save for military submarines and the occasional industrial accident, they’ve been extremely safe.

And even then, USN submarines are absurdly over-engineered. Or more aptly, they’re engineered to survive a massively hostile environment, even under multiple worst-case scenarios. FFS, the USS San Francisco slammed into an underwater mountain at flank speed at a depth of over 500 feet, and still managed to surface and get home under her own power. New sonar dome, ballast tanks, etc. and she was released for duty for another eight years.

This is only possible when you have multiple, redundant systems for everything.