That is 9,300 fathoms down.

The water is deep in this part of the river.

And I had to overcome my fear of deep water to find this one.

I had never seen black water before.

A depth of 40 meters...

Hover at 25 meters!

Still waters run deep.

Silent waters run deep.

There is an acute shortage of water.

(Laughter)

I then I don't know how it happened but I went underwater.

There is a problem with scuba, though, in that it imposes some limitations on how deep you can go.

It's a very deep water part of our planet.

There is many different aspects to free diving.

The water is deepest here.

An emergency return to the surface from 40 meters.

Still waters run deep.

But mostly I'm entranced by it.

The ocean contains most of the exchangeable heat on the planet.

And it's pictured right here, that little tag up there.

And if you look at the species level, you saw about fish.

One way trips are easy.

It's causing starvation. It's causing malnutrition.

It's 16 degrees Celsius here with a 12knot wind above the 97meterdeep sea

All divers have been down 40 meters.

Down and as the sun gets brighter they go a little deeper, little deeper.

Say you and your buddy are left alone at a depth of 40 meters.

You and your buddy are alone at a depth of 40 meters.

A depth of 40 meters... Just you and your buddy.

Even more critical are the water treatment and distribution systems.

A rescue exercise at 40 meters.

They also live deep.

This is the target site, the world's deepest hydrothermal spring at Cenote Zacaton in northern Mexico.

He took some deep breaths before he dived.

As we dive deeper, the water becomes colder.

But they have two types of gill structures.

It was actually developed for use by the offshore oil industry for diving on oil rigs down to a depth of 2,000 feet.

The high seas is a legal term, but in fact, it covers 50 percent of the planet.

So I tried to give up.

In the experimental EGS system, two shafts would be drilled 6 miles deep.

And I went down into my cabin and I put on my swimming costume.

Then he found out you were dumping water at night.

Water, water, water.

Usually we'll have a slightly larger cylinder, mounted exterior on the rebreather, like this.

And Sylvia Earle and I were on an expedition in this submarine 20 years ago in Japan.