In 1970, scientists in the Soviet Union set out to drill the deepest hole in the world.

They weren't drilling for oil or gas. They were just drilling for the sake of drilling to see what they could find.

And they actually found quite a lot.

Learn about the KOLA super deep borehole, the deepest hole on planet Earth,

on this episode of Everything Everywhere Daily. Do you really know how the internet works?

Can you even explain what communism actually is?

Have you ever asked yourself, how did I not know that?

I'm Jack, and I'm Nat, and we're the host of How Did We Not Know That, a podcast that covers all the things that you should know but don't.

Listen as we have unscripted conversations about child labor, secret wars, and stock market crashes.

Fine, how did we not know that wherever you listen to podcasts?

Before we dive down the hole on this topic, pun fully intended,

we should do a brief review of how the earth is structured.

At the top, the part we live on is called the crust.

The crust is actually quite thin in the big scheme of things.

The crust makes up less than 1% of the volume of the Earth and it's only about 5 to 70

kilometers deep depending on where you are on the planet.

The crust is thinner on the oceans and much thicker on land

especially under mountain ranges. Below that is the mantle which makes up the

vast majority of the volume of the

majority of the Earth's core. The boundary between the crust and the mantle is called the Mohirovich

discontinuity or the Moho layer.

Scientists wanted to get an actual piece of that part of the Earth.

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