Knowing the ocean floor better than your opponents is likely to be a big advantage when playing the various cat and mouse games with attack and ballistic missile subs that the US and the Soviet Union played for decades.
In 2015 USS San Francisco collided underwater sea mount at full speed. It was supposed to be deep blue sea.
In 2021 USS Connecticut collided with underwater mountain in South China Sea.
US Navy needs to map ocean floor only to 500 meters to keep it safe for submarines but they can't even do that.
I wouldn't be surprised if the uss connecticut was a resolution issue with the mapping system. And also I think it might be hard for the USN to get accurate maps of the south china sea currently.
"San Francisco's captain Commander Kevin Mooney was reassigned to a shore unit in Guam during the investigation of the collision. The Navy concluded that "several critical navigational and voyage planning procedures" were not being implemented aboard San Francisco, despite Mooney's otherwise remarkably good record. Consequently, the Navy relieved Mooney of his command and issued him a letter of reprimand."
"The seamount that San Francisco struck did not appear on the chart in use at the time of the accident, but other charts available for use indicated an area of "discolored water", an indication of the probable presence of a seamount. The Navy determined that information regarding the seamount should have been transferred to the charts in use—particularly given the relatively uncharted nature of the ocean area that was being transited—and that the failure to do so represented a breach of proper procedures.
Nonetheless, a subsequent study by UMass Amherst indicated that the Navy's charts did not contain the latest data relevant to the crash site because the geographical area was not a priority for the Defense Mapping Agency"
source: https://en.wikipedia.org/wiki/USS_San_Francisco_(SSN-711)
So it looks like the USN charts are not exactly cheap to generate. And there is a large human element of knowing where the charts are mostly accurate and where there is information missing.
Also keep in mind both of these are attack submarines and not Ohio class which generally are routinely patrolling the sea very deep and remaining as operationally quiet as possible to act as nuclear deterrents.
I think their track record is more interesting because they have to patrol and be extremely quiet (zero sonar).
The SSN/fast attack subs usually are escorting other groups / actively following targets so they end up in situations they can't entirely control.
First, it was 2005, not 2015.
Second, the seamount they struck was marked on charts the crew had as a potential hazard, they failed to review those charts and transfer the notation to the chart used for navigation.
> In 2021 USS Connecticut collided with underwater mountain in South China Sea.
And not long before that, with a pier at Naval Base Point Loma.
but could they just reduce the power of the sonar?
One could do some mapping by listening to the reverberations from underwater rock slides and other naturally occurring sources of sounds--if you just so happen to find yourself in the right spot at the right time.
US Navy has 7 Pathfinder-class survey ships under Naval Oceanographic Office scanning the ocean.
Most of the ocean floor is very deep, so deep that even modern submarines can't reach it. If I were a non-human, intelligent species, that would be a perfect place to hide.
The average depth of the Pacific ocean is around 4000 meters. The average depth of the Atlantic is about 3600 meters.