Despite living on a planet that’s 71% ocean, we’ve barely scratched the surface of what’s actually down there. By most estimates, fewer than 5% of the oceans have been explored in any kind of detail, and only about 20% of the seafloor has been mapped at high resolution.
For comparison, we have far better maps of the Moon, Mars, and even Venus than we do of our own planet’s seafloor. Most of the deep ocean has only ever been observed from above by sonar or in occasional fly-bys by remote-controlled vehicles.
The deepest point in the ocean - the Challenger Deep, in the Mariana Trench, at almost 11,000 meters down - has been visited by exactly a handful of people in submersibles. Twelve people have walked on the Moon. Far fewer have ever been to the bottom of the ocean.
