The Mariana Trench

Dive in to find out how far down the ocean goes and what it's really like at the bottom.

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Have you ever gone swimming in the sea and wondered how far down the ocean goes? The deepest known point on the planet is a mysterious cavern called Challenger Deep that plunges down inside a gigantic underwater valley called the Mariana Trench.

Located in the western Pacific Ocean, the Challenger Deep is so deep that if you stacked six Eiffel Towers on top of Mount Everest and put them inside, you still wouldn't break the sea surface. The Mariana Trench was first discovered in 1875 but is so hard to reach that only a handful of people have ever been there. It is one of the least explored places on the planet, and is teeming with mysteries. How can scientists learn about somewhere that is so treacherous to humans? Let's find out...

Going down

We now know that the Mariana Trench was created when two tectonic plates (huge, moving slabs of solid rock that make up the Earth's solid surface) slammed into each other and - in slow motion - one slid underneath the other creating a cavernous ditch.