I've made hundreds of dives in submersibles.

Like in a submarine, underwater?

444. The need for obtaining better information about the ocean floor has led to recent advances in diving apparatus, submersibles, remotely operated vehicles (ROVs) and self propelled autonomous underwater vehicles (AUVs).

Well... The diver who went down to inspect the bottom of the ship came across the hull of another boat.

They're sending a diver down. Muddy bottom down there, ain't it?

So you can imagine scuba diving here.

The problem happens when you start to go underwater.

But let's also think, as a visual species, what it's like when we go snorkeling or diving and try to look underwater.

Scuba divers can't get there, submarines go right on past it.

We know he's been taking girls out by boat.

Suddenly, Richard went under, not diving, but the way seals do, just sort of settling in the water.

It's been considered, Sir.

Ah, ama . Diving girls.

There is a problem with scuba though, in that it imposes some limitations on how deep you can go, and it turns out that depth is about 200 feet.

When I first went to the Maldives, dead keen on diving, spent as much of my time as I could in and under the water.

Can you swim underwater?

A dive more.

Dumas and Falco leave for explore the twilight zone at the foot of a cliff coral.

No, I don't want to die! I haven't done a thing.

I'll jump for it, I'm at home in the sea.

Now, submersibles are great, wonderful things, but if you're going to spend 30,000 dollars a day to use one of these things, and it's capable of going 2,000 feet, you're sure not going to go farting around up here in a couple of hundred feet, you're going to go way, way, way, down deep.

But, the point is that scuba divers generally stay less than 100 feet deep, and very rarely go much below this, at least, not with any kind of sanity.

They sent a diver down. He found another boat.

The recently developed AUVs are computer guided, untethered vehicles, capable of overcoming many of these problems, but are expensive.

This is why a man who descends to the sea, per meter down

I'd dive...

What about the submarine?

Stand by to winch in the submarine.

How about some skin diving?

If you look at this diagram of a coral reef, we know a lot about that part up near the top, and the reason we know so much about it is scuba divers can very easily go down there and access it.

Now I want to share with you a little video that I shot from a submersible.

There're three basic limitations of scuba diving.

Is the submarine there?

Look! Nautilus is just leaving.

So if you ever, ever get an opportunity to take a dive in a submersible, say yes a thousand times, yes and please turn out the lights.

And as you go down, the washing machine at the surface calms down.

The only creatures that have got conscious control of their breath are the diving animals and the diving birds.

These birds make a living by diving into the water.

It was an evening dive.

There is many different aspects to free diving.

How was the deepsea diver?

But scuba diving, submersibles and all the work that we're setting about to do here will help rectify that.

So, the bottom line is that almost all research using submersibles has taken place well below 500 feet.

They come right up to the submarine they'll put their eyes right up to the window and peek inside the sub.

The other primary way is we go down with submersibles and remote operated vehicles.