In the mid-20th century, when people looked at a map of the world, they saw the familiar continents surrounded by vast, ...

We’ve only mapped about 25 percent of the sea floor ... and ice,” and the new maps “will help us to answer some fundamental questions in tectonics and deep ocean mixing.” ...

More finely detailed maps of the surface of Mars may exist than of the remotest parts of the ocean floor. Scientists don’t often explore their slopes firsthand—or even their shallower summits ...