Naive suggestion from someone who has zero knowledge about these things: can't an unmanned submarine drone be constantly moving ahead of the main submarine to detect these obstacles before they become dangerous to the submarine and crew?
We also have highly classified models of the exact shape and mass distribution of the Earth, as this is essential to accurate long-range ballistics (i.e. for ICBMs to hit their targets) -- it affects the gravity experienced over the course, and the precision/accuracy needed is higher than just uniform-density sphere or oblate spheroid. Also of magnetic and other anomalies since that can be used as a baseline when searching for submarines or ships using magnetic sensors, although I think this is less important now.
“Maybe it would help to have a map of the space we’re going to be driving very large, very expensive, strategically important pieces of equipment (that also have crews) through blind” is not, as it turns out, something that never occurred to the Navy.
Project goal is 2030.
Or whiskers! That's how cats and catfish do it. A dozen 300' plastic prongs protruding frontward.
Or, to combine the two : TENTACLES!
Also, fishing trawlers, whales, etc.
Submarines are optimised in everything for absolute stealth, up to the point that the crew may not make any noise, like dropping a wrench.