Dive far below the sunlit surface into the ocean's deep, dark twilight and midnight zones — where pressure crushes submarines and some of Earth's strangest creatures glow in the dark.
Scientists split the ocean into zones by how much sunlight reaches them. The deepest zone, the Hadal Zone, is named after Hades — the ancient Greek underworld.
Sunlight fades completely by about 1,000 meters down — that's deeper than three Eiffel Towers stacked on top of each other. Below that, it's permanent night.
Around 90% of deep-sea animals can make their own light through a chemical reaction called bioluminescence, using it to hunt, hide, or find a mate in total darkness.
At the bottom of the Mariana Trench, water pressure is over 1,000 times what we feel at the surface — strong enough to crush most submarines instantly.
More than 80% of the ocean remains unmapped and unexplored — humans have better maps of the surface of Mars than of our own ocean floor.
Take the quiz and earn the Ocean Explorer badge for your Explorer Passport. Inspired by Kid Explorers: Secrets of the Deep Sea!