Where does everybody get this impression that the oceans are fully and completely charted? This has never been true, and likely won't be for a very long time to come.
Actually, only a fairly small portion of the ocean bottom is fully and accurately charted.
Yes, but wouldn't it make sense to at least complete the survey near a sub base (Guam)? Given that the Chinese are beginnning to deploy submarines in that area would make sense to have all the approaches charted and under observation with no gaps in the knowledge.
I don't know.