"Okay, I've lived near the ocean my entire life, and I still find this staggering: we literally live on an ocean planet. Earth should probably be called 'Ocean' — because that's mostly what it is. And the craziest part? We've explored less of the deep ocean than we've explored the surface of the Moon."
The Ocean Covers More of Earth Than You Think
We literally live on an ocean planet. Earth should probably be called 'Ocean' because that's mostly what it is. The ocean covers 71% of Earth's surface and holds 97% of all water on the planet. We have better maps of the Moon and Mars than of the ocean floor — less than 25% of the deep seafloor has been mapped in high resolution. The ocean contains about 1.335 billion cubic kilometers of water, a number almost impossible to visualize. The average depth is 3,688 meters (about 2.3 miles), and the deepest point — the Mariana Trench — is 10,935 meters deep, deeper than Mount Everest is tall. Sunlight only penetrates the top 200 meters of ocean; below that is the twilight zone, then permanent darkness, and life still exists there. If you spread all the salt in the ocean across Earth's land surface, it would form a layer 500 feet thick. And the ocean produces over 50% of Earth's oxygen — more than all the world's forests combined — mostly from microscopic phytoplankton.
