"20 meters below the surface, and that's only 2% of the ocean's total depth. We can go way deeper, and what we find along the way is nothing short of unbelievable. At 200 meters, you reach the twilight zone. Sunlight fades to darkness, sharks prowl, squid flash with light. Down here, bioluminescence is survival. It feels less like an ocean, and more like a galaxy alive beneath the waves. At 1,000 meters, the midnight zone. Here, no light ever reaches. The pressure? Like carrying 50 jumbo jets stacked on your chest. Or about 1,600 elephants pressing down at once. And still, creatures thrive. The giant squid and the anglerfish, in slanturn glowing in endless night. At 4,000 meters, welcome to the abyss. A frozen graveyard of shipwrecks. This is where the Titanic rests, preserved in silence since 1912. And in 2012, filmmaker James Cameron descended here alone, to see this alien world with his own eyes. At 6,000 meters, the hadal zone. Named for Hades, the underworld itself. Here, life clings to volcanic vents that spew boiling minerals from Earth's core. Creatures built not just to survive, but to endure the impossible. The bottom, 11,000 meters down. So deep that Mount Everest could sink here and still be swallowed whole. And just to make it easy for you, 11 kilometers is also the altitude where commercial planes fly. Except here, it's not sky above you, it's water. We've mapped Mars more clearly than our own oceans. And every dive reveals something new. Perhaps the strangest discoveries on Earth still wait for us in the deep."