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Hello, this is 6 Minute English from BBC Learning English. I'm Sam.

And I'm Neil.

The 20th of July 1969 was a big day in history. Do you know why, Sam?

Wasn't that when Neil Armstrong first set foot on the moon?

But it's often forgotten that some of the most dramatic photographs taken on the Apollo

space mission weren't of the moon at all. They were of earth.

It wasn't until we went to the moon that we really saw the size of earth's oceans and

named ourselves the blue planet.

Despite most of our planet being covered by water, the ocean remains a place of unexplored

mystery, of sea monsters like Moby Dick and the Kraken.

In this program, we'll be diving into the deep seas, seeing some of its strange sites and,

as usual, learning some related vocabulary too.

But before that, I have a question for you, Sam.

You were right when you said that most of the earth is covered by water,

but do you know exactly how much of the earth's surface is ocean?

Is it a 50% B 60% or C 70%?

Well, it is called the blue planet, so I'll say C 70%.

Okay, I'll reveal the answer later in the program.

The first thing to say about the deep ocean is that the rules of life down there are very

different from the rules on land. Sunlight cannot reach the very bottom of the ocean,

...