Strangford Lough Rock Pool Waterworld

Strangford's tides are legendary.

Billions of litres

rush through the narrows every day.

But there's a little-known corner of the lough

with a similar story to tell.

The Dorn Nature Reserve is a well-kept secret,

where a salt waterfall

cascades over kelp, just off the Newtownards to Portaferry Road.

It's one of the best rockpooling shores in the country,

and no-one knows it better than marine biologist

and all-round naturalist Pat Boaden.

Great sound. That's very spectacular, isn't it?

That's a marvellous sight, isn't it?

I don't know anywhere else in Northern Ireland or indeed Ireland

where I've seen a marine waterfall like this.

It's an extraordinary example

of a tidal rapids,

and tidal rapids are immensely valuable

because they have very, very rich species diversity,

especially of things that feed

by filtering out particles from the sea water.

Many of the creatures here

are usually only seen by divers in deeper water.

No matter where you look, Pat, there's life on the stones here. That's a great sponge.

This is one of the brick sponge, or rust sponge.

I think this is brick sponge.

The little holes in it are where the water current comes out.

There's sort of ingoing current that takes the food in,

little minute holes that are too small to see.

But then the currents come together

and they come out through these bigger holes in the side.

Look what we've got here.

This, I do believe... is a native oyster.

Of course, these days, you mostly get the Portuguese one

which has a wrinkly shell, but this, the native one,

is much flatter on one side than the other.

If you turn it over and look here,

you can just about work out how old it is

because these series of rings are just about annual.

So maybe this is 15 or so years old.

I didn't realise they got as old as that.

Oh, yes. I think the oldest one we ever found

was something like about 70 years old.

-70 years old?!

-It was about twice the size of this, really massive.

You never know what you're going to get underneath these.

-Indeed, you don't.

-There's more sponge.

-You mean down here?

-Yeah.

Well, you've not only got sponge, but look what you've got here.

Just let me lift these off.

There you are. Those are...

two sea slugs actually mating.

Those look like the sponge, and I suppose

that's probably a strategy for that species,

to look like something else.

They're very difficult to spot

cos they're often a very good match

to whatever sort of sponge they're on.

Strangford Lough is a very special place, and I think the longer

you work in it and look at it, the more special it becomes to you.

What's special about it?

It's the scenery,

the way the light changes -

you've got this interaction

between the sea and light and the water.

You couldn't ask for anything more tranquil at the moment.