Kristen Roe me is surrounded by dozens of ancient pyramids.

She's in the desert in Sudan.

It's dunes as far as you can see.

And Kristen's wearing scuba gear.

Okay, well this is going to top it all.

Let's go diving in a pyramid.

Kristen is an editor, writer, and one of my colleagues at National Geographic.

She's also an underwater archaeologist.

In the land she's investigated plenty of pyramids and ancient tombs.

This one is underneath the pyramid,

kind of like the basement.

There's a long set of stairs leading down to the tomb.

It's flooded with murky brown water, but Kristen dives in.

It was just zero visibility in the water and it was just like beige, beige, beige.

Boom, rock wall where I kept swimming into the sides of the chamber.

Actually, she crawls in through a narrow opening about the size of a television.

Feeling her way through the dark water, she finally reaches a larger chamber.

There were a couple times when I was working in there and heard a funk.

No splash into the water and something's falling into the water.

And it's not a snake, I know that.

So it's pieces of the tomb falling.

And then you've got like a really tiny, almost looks like a can of hairspray of emergency air.

...