This is very much a solved problem, for several decades now. US and Russian naval submarines routinely patrol for thousands of miles over weeks or months, witho

This is very much a solved problem, for several decades now. US and Russian naval submarines routinely patrol for thousands of miles over weeks or months, without surfacing. https://en.m.wikipedia.org/wiki/Submarine_navigation https://en.m.wikipedia.org/wiki/Submarine_navigation It's not mentioned in the article, but I believe US subs also have a long-tether communications buoy that can float to the surface, but not expose itself vertically, to communicate with satellites. I would be surprised if it did not also have a GPS antenna.