I'm fully aware that there's more to nautical charts than the water's surface, and I used the term 'satellite photography' somewhat broadly. More of the deep ocean has been mapped by sensors in polar orbits, which can stay on-station indefinitely and cover the entire globe without regard for local obstacles, than ever was (or likely would have been) by surface craft and submarines.
To quote the National Ocean Service:
...Yet for all of our reliance on the ocean, 95 percent of this realm remains unexplored, unseen by human eyes.
NOAA’s Office of Ocean Exploration and Research is leading efforts to explore the ocean by supporting expeditions to investigate and document unknown and poorly known areas of the ocean. These expeditions represent a bold and innovative approach by infusing teams of scientist-explorers with a "Lewis and Clark" spirit of discovery and equipping them with the latest exploration tools.
From mapping and desc
Another month, another rationality quotes thread. The rules are: