It needn’t even be that deep. Depending on the (known) depth of the surrounding sea floor, subs operate much shallower when necessary.
Whether known or unknown, slaloming around sea mounts is not a thing.
If Sean Connery can play a Lithuanian-born Russian submarine captain with a Scottish burr then I think the universe the story occurs in is one in which the physics allow submarines to fly through the water like jet fighters dogfighting.
Stranger
As I recall, Red Route One was mapped in exquisite detail by the Russians, and Captain Ramius had each detail memorised. That’s supposed to allow us to suspend belief.
If they had enough power to do hairpin turns in a 48000 ton submarine, I don’t know why they put it underwater at all. They could have flown that thing higher and faster than an SR71.
I’m pretty sure it was Connery’s performance and high quality toupée that was supposed keep the audience enthralled enough to not ask those questions, or inquire as to why Tim Curry was playing what was presumably intended to be a serious role as the boat’s physician without a hint of a Russian accent. Most of the crew at least made a reasonable attempt to sound Russian (a few even appear to speak with some fluency, or at least are ADRed by Russian-speaking actors); even Sam Neill makes a passable effort. No clue as to why Cathy Ryan was played by an American actress sporting a posh English accent, but it was still a better adaptation of any Tom Clancy novel that anything that has come since.
Stranger
I just read the first couple of pages of that novel and it already reads like the pulpiest technothriller trash you could imagine. I can’t wait to read more!
Stranger
By the time that you get to where you’re commanding a sub, your youthful mistakes should be long behind you.
Not to hijack, but the footage of the F-9F crashing onto the carrier deck still irks me. But yeah, it was a good adaptation of the novel (even though they left so much out). (Incidentally, Cathy’s Porsche in Patriot Games (IIRC) would not have had chrome on it as described in the book.)
And here I thought you were talking about Space Battleship Yamato…
Ringo writes some of the best speculative fiction and some of the worst. I think this one was fun.
I didn’t say anything about youthful mistakes. The U.S. Navy has zero tolerance for any mistakes whatsoever. The only way to never make a mistake is to either be very lucky or very risk-averse.
With that said, I don’t mean to condone a mistake that is the result of gross negligence or that leads to loss of life.
The point of mentioning Chester Nimitz is the fact that in today’s U.S. Navy, after receiving a letter of reprimand he would never promote and would subsequently be involuntarily separated from service.
I don’t believe this is correct. Multibeam echo sounders are the primary means of mapping bathymetry, sidescans are used more for object detection and identification as well as bottom classification. I am a hydrographer and that is how I use them anyway.
From your link: “Side scan cannot measure bathymetry (depth), so it is often used in tandem with depth-measuring tools such as single beam and multibeam sonar in order to create a more comprehensive map of the seafloor.”
An informative link: https://www.frontiersin.org/articles/10.3389/fmars.2019.00283/full
Also: GEBCO Overview
I’m honestly surprised that Naval Intelligence doesn’t have its own mapping section. Getting accurate maps of your area of operations is Intelligence 101.
Uh, no. 
It isn’t often I get to correct Stranger!
The US Naval Oceanographic Office has the responsibility of bathymetric surveying of all the oceans outside the coastal waters of the US. They have been doing this for the last 150+ years.
I was going to link to the NAVOCEANO website. Talk about a minimal site! The wiki at least says something.
NAVOCEANO has several departments one of which is the hydrographic department. They operate several purpose built hydrographic survey ships worldwide.
Most of the major sea powers operate similar programs. The US Navy is the largest.
The IHO sets international standards and holds conferences. I haven’t ever heard of them actually conducting any surveys.
There are several organizations that specialize in mapping. NAVOCEANO handles world-wide bathymetry. Naval intelligence and Navy strategic forces rely on NAVO. The largest mapping organization is the National Geospatial Agency. Military grade maps of the entire world is their specialty. They also have tactical roles (targeting), intelligence, R&D, satellite operations, and lots of other things that they can’t talk about.
Combined the military spends several billion $/year on creating, updating, and maintaining paper and digital maps of the entire world.
Not to mention having some rather extensive and expensive contracts with ESRI. I have students who work for them, and a lot of the stuff they do is at the very least seconded to the military.
The mysterious disappearance of Malaysia Airline 370 highlighted how poorly mapped the sea floor is in the vast area that needed to be searched.
I expect the worlds navies concentrate their underwater surveys in areas of strategic importance where they may come in contact with the navies of rival states. Undersea mounts are features probably only relevant to submersibles in the comparatively shallow waters of the continental shelves near to some port or strait or island base.
75% of the world is covered by ocean greater than 1000m in depth. Way deeper than the operating range of many submarines. So if there are no rival submarines down there and it is not near any strategic location, there is little reason to survey much of the sea floor which is an expensive and time consuming activity. There are probably a great many sea mounts are other features that are completely unknown.
The resolution of undersea surveys is also quite modest. Satellite information can resolve features at 5km per pixel. Sonar surveys down to 100m per pixel? The maps are not very accurate at depth and the topography of the sea floor changes over time. Changes cannot be captured without regular surveys and there will be uncharted hazards.
Hot spots like the South China Sea are unlikely to be the easiest places for surface ships to survey given the tensions in the area.
It seems China has been trying to stop undersea surveys for some time:
One day, I expect there some clever satellite or aircraft based technology will emerge that will be able to peer down into the abyss and map out what is down there easily. If such a technology does emerge, I expect it will be kept secret for many years given its strategic value.
Do you have to use submarine to map the ocean floor? Can’t you just dump lots and lots of sonobuoys?
The search for the MH370 airliner used these ‘tow fish’ for their sonar surveys.
Quite easy to lose them by accident as this one was. Apparently it bumped into an underwater ‘mud volcano’.
Towing anything from a surface ship is very vulnerable to disruption from other vessels, especially a hostile navy such as that of China keen to keep other navies out of the South China Sea. It is easy to cut tow lines.