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

The image below shows a bathymetric map of the ocean floor, where pink denotes the shallowest water (continental shelves and ...

The map depicts the mid-ocean ridge zigzagging its way around the world. It looks like if you ran your fingers over the paper, you'd be able to feel where it rises and falls.

The image below shows a bathymetric map of the ocean floor, where pink denotes the shallowest water (continental shelves and oceanic plateaus), compared with the yellow-green of mid-ocean ridges ...

Topographic or satellite maps of Earth may reveal ridges and troughs that crisscross flat plains on the ocean floor, making it seem as though the entire ocean floor has been mapped out, Ferrini said.

NASA's Surface Water and Ocean Topography satellite, aka SWOT, has provided one of the most detailed maps of the seafloor ever created.