[crote]

It's public knowledge that the US Navy has its own fleet of surveying vessels, concluding that they actually use them as well isn't much of a stretch.

[vundercind]

I’ve had no access to classified anything ever and could have told you the US navy has remarkably good maps of several key parts of the ocean in which friendly or enemy boomer subs are likely to operate.

Like, of course they do. If there are any unusually-good ocean maps they have, it’s those, at least.