0:00:00 > 0:00:00- Subtitles
0:00:00 > 0:00:02- Subtitles- - Subtitles
0:00:06 > 0:00:07- I'm Iolo Williams.
0:00:07 > 0:00:12- I've spent years studying wildlife - on land and in the air.
0:00:13 > 0:00:16- This time, - I'm venturing into a new world.
0:00:18 > 0:00:22- I'll be looking for creatures - I've never seen before.
0:00:27 > 0:00:32- I'm travelling to Australia - to dive under the sea...
0:00:32 > 0:00:35- ..to see - one of our planet's treasures.
0:00:37 > 0:00:39- This is the Great Barrier Reef.
0:00:40 > 0:00:44- It extends over 1,000 miles - off the coast of northern Australia.
0:00:58 > 0:01:01- But this important part - of our ecosystem...
0:01:01 > 0:01:03- ..is in danger.
0:01:04 > 0:01:06- It's sad coming here - and seeing this happen.
0:01:07 > 0:01:09- It could disappear...
0:01:14 > 0:01:15- ..in 80 years.
0:01:23 > 0:01:28- Will children of the future be able - to enjoy this special place?
0:01:58 > 0:02:01- I'm on my way to Yorkeys Knob.
0:02:02 > 0:02:05- In the harbour, - I will meet the crew and boat...
0:02:06 > 0:02:08- ..that will take me - on a magical journey.
0:02:19 > 0:02:22- The Great Barrier Reef - is located in the Coral Sea...
0:02:23 > 0:02:25- ..to the north of Queensland state.
0:02:36 > 0:02:40- I'll visit the reef to see - as much of the wildlife as I can.
0:02:46 > 0:02:49- I'll also assess its condition.
0:02:49 > 0:02:51- This is a liveaboard boat.
0:02:51 > 0:02:52- It's quite large.
0:02:53 > 0:02:56- We're living on it for four nights.
0:02:57 > 0:03:01- We're going to the far side - of the reef.
0:03:01 > 0:03:04- It'll take us about ten hours - to get there.
0:03:05 > 0:03:07- We're leaving just before dusk.
0:03:07 > 0:03:12- I hope when I wake up tomorrow, - we'll have arrived at the reef.
0:03:25 > 0:03:29- I'm really looking forward - to diving down.
0:03:29 > 0:03:33- I hope to see some of the best reefs - with all its wildlife.
0:03:46 > 0:03:49- I also want to see how bad it is.
0:03:49 > 0:03:54- Are there reefs - where there's no life left?
0:04:07 > 0:04:10- At last, I'm getting the chance - to see for myself...
0:04:10 > 0:04:12- ..how bad it is out there.
0:04:37 > 0:04:42- We've travelled overnight - to reach Ribbon Reef No.3.
0:04:55 > 0:05:00- This will be my first opportunity - to see the place with my own eyes.
0:05:08 > 0:05:11- I'm wearing a full face mask - for the dives...
0:05:12 > 0:05:14- ..so I can speak underwater.
0:05:25 > 0:05:29- I know I understand very little...
0:05:29 > 0:05:33- ..about the ecology of the reef - and its wildlife.
0:05:33 > 0:05:37- The way it works and the way - the wildlife exists together.
0:05:37 > 0:05:39- The relationships there.
0:05:40 > 0:05:43- If I can dive and learn - a bit more about the reef...
0:05:43 > 0:05:46- ..I'll return home a very happy man.
0:06:15 > 0:06:19- The reef is crucial for - the ecosystem of the entire world.
0:06:19 > 0:06:24- It releases moisture to keep the - environment cool and moist enough...
0:06:24 > 0:06:27- ..for forests and plants to grow.
0:06:32 > 0:06:36- This special place underwater - releases oxygen for us to breathe.
0:06:41 > 0:06:45- However, there's more - carbon monoxide in the atmosphere.
0:06:45 > 0:06:50- The seas are becoming more and more - acidic which kills the coral.
0:06:51 > 0:06:56- The Great Barrier Reef - is 2,400km long.
0:06:56 > 0:07:00- 1,500 miles from north to south.
0:07:01 > 0:07:04- Many think - it's one long unbroken line.
0:07:04 > 0:07:06- That's not true.
0:07:06 > 0:07:10- It's made up - of thousands of different reefs.
0:07:10 > 0:07:13- Some of them as small as this.
0:07:30 > 0:07:31- It's incredible.
0:07:31 > 0:07:35- There are fish and coral - all around me.
0:07:55 > 0:07:58- I've dived - to see the condition of the reef...
0:08:00 > 0:08:05- ..and to see if this is the last - chance to see a miracle of nature.
0:08:07 > 0:08:10- One of the things - that strikes you first...
0:08:11 > 0:08:14- ..is that most of the coral here - is brown.
0:08:14 > 0:08:17- From what we've seen - on television...
0:08:17 > 0:08:21- ..we're used to seeing blue, red, - pink and yellow coral.
0:08:21 > 0:08:27- The truth is that the majority - of coral is brown.
0:08:27 > 0:08:29- The brown coral is live coral.
0:08:30 > 0:08:33- Only a few of them - are brightly-coloured.
0:08:34 > 0:08:37- It's real coral.
0:08:42 > 0:08:46- Seeing all this coral is like - finding a small forest underwater.
0:08:50 > 0:08:55- I'm not surprised that scientists - used to think coral were plants.
0:08:58 > 0:09:00- There's some truth in that.
0:09:05 > 0:09:08- Coral are small animals - that look like plants.
0:09:09 > 0:09:12- They live on small fish - and plankton.
0:09:14 > 0:09:17- A reef forms - when the coral larvae spawns...
0:09:17 > 0:09:20- ..and attaches to submerged rocks.
0:09:21 > 0:09:26- It's dependent on the water quality - and the sun's rays to survive.
0:09:30 > 0:09:32- It's important - to keep the balance...
0:09:32 > 0:09:36- ..between the different parts - of the life cycle on the reef.
0:09:37 > 0:09:41- One small change in water quality - or the temperature...
0:09:42 > 0:09:45- ..can have a detrimental effect.
0:09:51 > 0:09:53- This is an interesting coral...
0:09:54 > 0:09:57- ..staghorn coral.
0:09:57 > 0:10:01- It grows extremely quickly...
0:10:02 > 0:10:05- ..about 10cm every year.
0:10:05 > 0:10:09- As you can see, the small fish - are delighted with it.
0:10:26 > 0:10:28- There's a contrast...
0:10:28 > 0:10:33- ..between the beautiful, colourful - yellow coral here...
0:10:33 > 0:10:35- ..and the dead coral here.
0:10:35 > 0:10:39- It's grey and covered with algae.
0:10:39 > 0:10:43- It's very sad to see that.
0:10:48 > 0:10:52- It was so disheartening - to see the damage to the coral.
0:10:53 > 0:10:57- It's obvious that these - are tough times for the reef.
0:11:10 > 0:11:14- But around the corner, - I saw something spectacular.
0:11:37 > 0:11:39- Look at all these yellow fish!
0:11:39 > 0:11:44- It's as if all the yellow fish - have agreed to come together.
0:11:44 > 0:11:47- There are two species here...
0:11:47 > 0:11:50- ..the yellow snapper - and the yellow goatfish.
0:11:51 > 0:11:56- It's better to be one of a thousand - than to be alone.
0:11:57 > 0:12:00- There are predatory fish around.
0:12:00 > 0:12:02- They school for safety.
0:12:46 > 0:12:48- That's blown my mind.
0:12:49 > 0:12:51- The only way I can describe it...
0:12:51 > 0:12:57- ..is it's like jumping into - the biggest and best aquarium ever.
0:12:57 > 0:13:01- The coral of different colours - and different shapes...
0:13:01 > 0:13:02- ..and so many fish.
0:13:03 > 0:13:04- What an experience.
0:13:05 > 0:13:07- It'll stay with me forever.
0:13:18 > 0:13:18- .
0:13:22 > 0:13:22- Subtitles
0:13:22 > 0:13:24- Subtitles- - Subtitles
0:13:33 > 0:13:37- I'm on a journey along - the Great Barrier Reef in Australia.
0:13:51 > 0:13:57- After a day and a half's travelling, - we've reached Pixie's Pinnacle...
0:13:57 > 0:14:00- ..between Ribbon Reef No.9 - and Ribbon Reef No.10.
0:14:21 > 0:14:26- I'm about to dive in a place - called Pixie's Pinnacle over there.
0:14:26 > 0:14:31- We're about 30 miles off the coast - of north-east Australia.
0:14:31 > 0:14:34- It's like a chimney coming up.
0:14:34 > 0:14:38- As it's a chimney, - there are lots of small fish around.
0:14:38 > 0:14:40- That in turn attracts big fish.
0:14:50 > 0:14:53- The reef's - coming under increasing pressure.
0:14:53 > 0:14:57- Global warming's caused - the water temperature to rise.
0:14:57 > 0:15:00- Chemicals are flowing from the land - to the sea.
0:15:02 > 0:15:04- These are killing the coral.
0:15:09 > 0:15:12- This is a crucial period - in their history.
0:15:12 > 0:15:15- To be honest, - it's making me worried.
0:15:47 > 0:15:51- The argument that global warming - affects the reef...
0:15:51 > 0:15:54- ..is one - that everybody accepts today.
0:15:55 > 0:15:57- It would break my heart...
0:15:57 > 0:16:01- ..if my son wanted to come here - in 50 years...
0:16:01 > 0:16:05- ..and there was no reef left, - or only a dead reef.
0:16:19 > 0:16:23- A vital part of the health - of the reef is the food chain.
0:16:23 > 0:16:26- If the reef's under pressure - and suffering...
0:16:26 > 0:16:29- ..there'll be less food - for the fish.
0:16:29 > 0:16:33- So I want to find out the state - of the food chain in this part.
0:16:53 > 0:16:55- What a fish this is!
0:16:56 > 0:16:58- It's a great barracuda.
0:16:59 > 0:17:02- The barracuda has a bad name.
0:17:02 > 0:17:04- It isn't deserved.
0:17:04 > 0:17:06- All it does is hang around.
0:17:07 > 0:17:11- It'll come in now and again - to eat the small fish.
0:17:11 > 0:17:13- It rushes in.
0:17:13 > 0:17:15- If you look at its body...
0:17:15 > 0:17:18- ..it's all muscle with a big mouth.
0:17:19 > 0:17:22- It goes straight in - chasing after the fish.
0:17:37 > 0:17:41- The food chain on the reef - is a very sensitive ecosystem.
0:17:41 > 0:17:45- It needs to be in balance - with the natural world around it.
0:17:47 > 0:17:50- On top of the chain - are fish like the barracuda.
0:17:55 > 0:17:58- At the bottom are the phytoplankton.
0:18:02 > 0:18:07- I'm so happy to see that this - part of the reef looks so healthy.
0:18:57 > 0:19:01- Look at the small fish - all around me.
0:19:01 > 0:19:04- Thousands and thousands of them.
0:19:04 > 0:19:06- Incredible!
0:19:07 > 0:19:09- They all eat plankton.
0:19:09 > 0:19:15- What's interesting is that some of - them stay very close to the coral.
0:19:16 > 0:19:19- Others venture further out.
0:19:20 > 0:19:22- Look at their tails.
0:19:23 > 0:19:28- The ones who venture out - have a V-shaped tail.
0:19:28 > 0:19:31- It means they're fast swimmers.
0:19:40 > 0:19:44- It's important that algae levels - on the reef remain constant.
0:19:45 > 0:19:49- That's the main function - of a sea fan.
0:19:56 > 0:19:58- It's very pretty.
0:19:58 > 0:20:01- The sea fan.
0:20:01 > 0:20:04- It grows facing inwards...
0:20:05 > 0:20:09- ..at an angle of 90 degrees - into the current.
0:20:10 > 0:20:12- The current - runs through the sea fan.
0:20:14 > 0:20:18- The polyps, the hundreds of - small creatures that live in it...
0:20:19 > 0:20:21- ..are filter feeders.
0:20:22 > 0:20:26- They draw nutrients from the water.
0:20:26 > 0:20:30- If they grow like this - and the current comes through...
0:20:30 > 0:20:33- ..they have access - to so much more food.
0:20:34 > 0:20:38- They're in the darkness because - they don't use energy from the sun.
0:21:10 > 0:21:11- Oh!
0:21:12 > 0:21:13- A sea turtle.
0:21:14 > 0:21:15- A green turtle.
0:21:16 > 0:21:19- I've never been in the sea - with one before.
0:21:19 > 0:21:22- It's come down to say hello.
0:21:22 > 0:21:24- Goodness me!
0:21:25 > 0:21:29- They're known here - as the old men of the sea.
0:21:29 > 0:21:33- Seeing one up close, - I could see why.
0:21:34 > 0:21:37- They look like - they know all the reef's secrets...
0:21:38 > 0:21:42- ..after swimming around the place - for thousands of years.
0:21:45 > 0:21:50- I'm not sure how old this one is - - about 30 or 40 years old.
0:21:50 > 0:21:54- She'll return every other year...
0:21:54 > 0:21:57- ..to nest - on a remote beach somewhere.
0:22:00 > 0:22:03- They're vital to the reef's - food chain.
0:22:03 > 0:22:06- They keep box jellyfish numbers - in check...
0:22:06 > 0:22:11- ..who in turn keep plankton - and mollusc numbers healthy.
0:22:13 > 0:22:17- They enjoy having - their shell scratched...
0:22:17 > 0:22:19- ..like this one is now.
0:22:20 > 0:22:21- I think I must be tickling it.
0:22:22 > 0:22:24- She loves it.
0:22:26 > 0:22:29- I feel like a person - who cleans cars!
0:22:33 > 0:22:35- Go now, darling.
0:22:41 > 0:22:42- Go now.
0:22:42 > 0:22:44- Off you go.
0:22:44 > 0:22:46- She's so cute.
0:22:46 > 0:22:48- Look at her.
0:22:51 > 0:22:54- She's coming back for more!
0:22:54 > 0:22:56- More scratching.
0:22:57 > 0:22:59- There we are.
0:22:59 > 0:23:01- Is that nice?
0:23:01 > 0:23:03- Enough scratching.
0:23:13 > 0:23:15- They're so graceful.
0:23:24 > 0:23:25- What an experience!
0:23:26 > 0:23:28- A sea turtle coming to say hello.
0:24:04 > 0:24:05- Cheers, lads.
0:24:07 > 0:24:09- That was incredible.
0:24:09 > 0:24:12- A green turtle came up to me...
0:24:12 > 0:24:16- ..and remained still - until I scratched its back.
0:24:16 > 0:24:19- It was so contented. - Its eyes were half closed.
0:24:20 > 0:24:21- Then off it went.
0:24:21 > 0:24:26- Things like that don't happen often. - When they do, they're incredible.
0:24:27 > 0:24:27- .
0:24:41 > 0:24:41- Subtitles
0:24:41 > 0:24:43- Subtitles- - Subtitles
0:24:56 > 0:25:00- I'm travelling along - the Great Barrier Reef...
0:25:00 > 0:25:02- ..and the surrounding coast.
0:25:12 > 0:25:15- I'm on my way - to the Daintree Rainforest...
0:25:16 > 0:25:18- ..a stone's throw from the coast.
0:25:20 > 0:25:23- Tropical rainforests - like the Daintree...
0:25:23 > 0:25:26- ..are vital - to the health of the reef.
0:25:29 > 0:25:32- It's like a wall - between the land and the sea.
0:25:33 > 0:25:37- The reef itself - releases moisture into the air...
0:25:37 > 0:25:40- ..above the rainforest, - keeping it healthy.
0:25:56 > 0:25:59- We're going down the Barron River.
0:25:59 > 0:26:03- This is one of the main rivers - that flows into the sea...
0:26:03 > 0:26:06- ..and then - to the Great Barrier Reef.
0:26:06 > 0:26:10- What's nice coming down this river - is I can't hear people.
0:26:10 > 0:26:14- I can hear birds with just - the natural world around me.
0:26:14 > 0:26:16- The tropical forest.
0:26:16 > 0:26:19- You can hear lorikeets - making a lot of noise.
0:26:19 > 0:26:22- It's great - to be somewhere like this...
0:26:22 > 0:26:25- ..away from cities and towns - and their noise.
0:26:27 > 0:26:29- The river's important - to the reef too.
0:26:29 > 0:26:32- You just - have to look at its colour...
0:26:32 > 0:26:36- ..to see there are all sorts - of tiny pieces of mud...
0:26:37 > 0:26:41- ..and organic matter - in the water...
0:26:41 > 0:26:44- ..because there's been flooding.
0:26:44 > 0:26:48- They, along with the fallen leaves - are washed out to sea...
0:26:48 > 0:26:49- ..out to the reef...
0:26:50 > 0:26:54- ..which is food for many of the - tiny creatures that live there...
0:26:54 > 0:26:56- ..such as plankton.
0:26:56 > 0:26:58- Plankton feed the fish...
0:26:58 > 0:27:02- ..and the fish feed the bigger fish - and the sharks and so on.
0:27:03 > 0:27:06- This is a very important part - of that food chain.
0:27:08 > 0:27:12- The fact there's a lot of water - in the river...
0:27:12 > 0:27:16- ..can also mean - it's the worst time for chemicals...
0:27:17 > 0:27:20- ..to be washed into the sea - from farms.
0:27:20 > 0:27:25- It's sprayed on crops, on sugar cane - more than anything else.
0:27:25 > 0:27:30- That affects the Great Barrier Reef - and the wildlife.
0:27:45 > 0:27:50- One of the biggest challenges facing - the reef is poor water quality.
0:27:52 > 0:27:55- The water quality - is primarily affected...
0:27:55 > 0:27:58- ..by intensive sugar cane farming.
0:28:00 > 0:28:03- Water polluted by chemicals...
0:28:03 > 0:28:06- ..spurs - the crown-of-thorns starfish.
0:28:07 > 0:28:12- It's a destructive starfish which - grows on top of healthy coral...
0:28:14 > 0:28:15- ..and kills it.
0:28:24 > 0:28:27- I wanted to find out - how the local farming community...
0:28:27 > 0:28:29- ..felt about the reef...
0:28:30 > 0:28:34- ..and how their farming methods - could be so destructive.
0:28:37 > 0:28:41- I've come to meet a local farmer - who's changed his farming methods...
0:28:41 > 0:28:43- ..in order to save the place.
0:28:44 > 0:28:46- I wanted to find out why.
0:28:50 > 0:28:53- As a local man, - what does the reef mean to you?
0:28:53 > 0:28:56- What happens if the reef disappears?
0:28:56 > 0:28:57- What happens if the reef disappears?- - It means everything to me.
0:28:58 > 0:29:01- I've spent my entire life - living on the Queensland coastline.
0:29:02 > 0:29:04- I want to go to the reef - when I have days off.
0:29:04 > 0:29:08- I want a healthy reef. I want to be - able to fish on the reef.
0:29:08 > 0:29:13- It upsets me that my kids - won't see the reef like I saw it.
0:29:18 > 0:29:22- Dave wanted to show how his - farming methods affected the reef.
0:29:26 > 0:29:31- If the reef disappeared, Dave's way - of life would come to an end too.
0:29:38 > 0:29:42- This creek runs through your land - out of the rainforest into the sea.
0:29:42 > 0:29:45- Straight into - the Great Barrier Reef lagoon.
0:29:45 > 0:29:48- Effectively, - this is my responsibility.
0:29:48 > 0:29:53- What I do on my land - affects this river directly...
0:29:53 > 0:29:57- ..and affects - the Great Barrier Reef as well.
0:29:57 > 0:30:01- Other landowners, there are - going to be creeks like this...
0:30:01 > 0:30:04- ..that run through - fairly intensively-farmed land.
0:30:05 > 0:30:08- That's where some of the problems - arise.
0:30:08 > 0:30:10- Yes, you're exactly right.
0:30:11 > 0:30:14- So, really, it's nitrogen run-off.
0:30:15 > 0:30:19- We've got really high rainfall here, - of course. A rainforest area.
0:30:19 > 0:30:22- That high rainfall - can leach some of the nutrients...
0:30:22 > 0:30:26- ..that's not absorbed by the plants - into these waterways.
0:30:26 > 0:30:28- It's the nitrogen especially...
0:30:28 > 0:30:32- ..but it's also the clouding - of the water column...
0:30:32 > 0:30:37- ..which can affect how coral - catch sunlight to make their food.
0:30:37 > 0:30:40- But also, intensive farming - can affect sediment run-off.
0:30:41 > 0:30:44- It can create massive amounts - of erosion around rivers.
0:30:45 > 0:30:48- That sediment again - can cloud that water column...
0:30:49 > 0:30:52- ..leading to pretty bad impacts - down the road.
0:30:52 > 0:30:53- How worried are you?
0:30:54 > 0:30:58- I think this year has been - the first year I've realized...
0:30:58 > 0:31:02- ..that this could impact my life.
0:31:02 > 0:31:06- If the health of - the Great Barrier Reef declines...
0:31:06 > 0:31:10- ..it stands to reason - that people will stop visiting...
0:31:10 > 0:31:14- ..and my businesses will slide - into decline very quickly.
0:31:14 > 0:31:17- I think that's true - of a lot of other businesses...
0:31:18 > 0:31:21- ..and maybe - they don't quite realize it.
0:31:31 > 0:31:36- I'm glad I made the time - to meet and chat with Dave...
0:31:36 > 0:31:39- ..mostly because he's a local man.
0:31:39 > 0:31:42- He's lived in the area all his life.
0:31:45 > 0:31:50- Maybe one of the most important - things is he's farming organically.
0:31:50 > 0:31:54- He knows that chemicals from farms - that go into the sea...
0:31:54 > 0:31:56- ..affect the reef.
0:31:56 > 0:32:02- If everyone was like him, we - would be in a much better situation.
0:32:05 > 0:32:08- The more - I speak to people like David...
0:32:08 > 0:32:11- ..the more I realize - I know very little.
0:32:16 > 0:32:19- I hadn't realized the close link...
0:32:19 > 0:32:22- ..between the reef - and the tropical forest.
0:32:23 > 0:32:27- Without one, you don't get - the other. Both are essential.
0:32:28 > 0:32:30- If the reef disappears...
0:32:30 > 0:32:33- ..the effects will be terrible...
0:32:34 > 0:32:40- ..on wildlife, local people, - Australia and on the world.
0:32:49 > 0:32:53- As I leave Dave's farm, - I saw an unforgettable sight.
0:33:20 > 0:33:21- Wow!
0:33:22 > 0:33:25- This is one of the birds - I hoped to see here.
0:33:26 > 0:33:29- I really didn't think I'd see it.
0:33:29 > 0:33:31- It's a cassowary.
0:33:31 > 0:33:34- It's Australia's answer - to the ostrich.
0:33:34 > 0:33:39- It only lives in this forest - so it's very rare.
0:33:41 > 0:33:46- This is a small farm - right in the middle of the forest.
0:33:46 > 0:33:49- He's opened up the land. - He's planted fruit trees.
0:33:50 > 0:33:52- That's why the bird's here.
0:33:52 > 0:33:55- It comes out of the forest to eat.
0:33:55 > 0:33:59- It goes down to the river for - a drink then returns to the forest.
0:34:01 > 0:34:04- They can't fly at all - but they don't need to.
0:34:04 > 0:34:07- They can run very fast.
0:34:07 > 0:34:12- This is the male with five chicks.
0:34:12 > 0:34:17- The female lays the eggs - on the ground in the forest.
0:34:17 > 0:34:19- She then leaves.
0:34:19 > 0:34:21- The male sits on the eggs.
0:34:21 > 0:34:24- When they hatch, - he looks after the chicks.
0:34:25 > 0:34:28- He's come to these trees - as fruit has fallen.
0:34:29 > 0:34:30- He's come to eat.
0:34:31 > 0:34:34- They can be very dangerous birds.
0:34:34 > 0:34:39- As long as you give them space and - show some respect, you'll be fine.
0:34:40 > 0:34:41- He's fierce.
0:34:41 > 0:34:43- I won't get too close.
0:34:43 > 0:34:46- He'll defend the chicks - with those long legs.
0:34:46 > 0:34:48- He kicks.
0:34:48 > 0:34:50- He could open up my stomach.
0:34:55 > 0:34:58- Come down this way.
0:35:09 > 0:35:11- Here he is now.
0:35:11 > 0:35:13- The chicks. Look at that.
0:35:22 > 0:35:25- That's made my day.
0:35:25 > 0:35:27- My year.
0:35:27 > 0:35:29- I never thought I'd see a cassowary.
0:35:30 > 0:35:33- I have a male with five chicks - right in front of me.
0:35:36 > 0:35:36- .
0:35:46 > 0:35:46- Subtitles
0:35:46 > 0:35:48- Subtitles- - Subtitles
0:36:03 > 0:36:09- I'm going on a very special trip and - diving in the Great Barrier Reef.
0:36:14 > 0:36:17- Tonight, - I'm going underwater at night.
0:36:26 > 0:36:29- I'm 12 miles out in the Coral Sea...
0:36:29 > 0:36:31- ..about a third of the way - down the reef.
0:36:37 > 0:36:40- I'm preparing to go diving - at night.
0:36:40 > 0:36:44- Diving at night is very - different to diving during the day.
0:36:45 > 0:36:46- It's more exciting.
0:36:46 > 0:36:49- There are very different creatures - out.
0:36:49 > 0:36:52- The ones active during the day - go to sleep.
0:36:52 > 0:36:55- There are others - who only come out at night.
0:36:56 > 0:37:02- I hope to see a fish - called stonefish.
0:37:02 > 0:37:05- It's the most poisonous fish - in the world.
0:37:05 > 0:37:07- Its camouflage is perfect.
0:37:07 > 0:37:10- I'll need a good lamp to find one.
0:37:13 > 0:37:17- This is my first night-time dive - in the Great Barrier Reef.
0:37:18 > 0:37:20- It's exciting but I'm a bit nervous.
0:37:29 > 0:37:33- It's impossible to know - what will be down there.
0:38:54 > 0:38:57- The reef is a very different place - at night.
0:39:00 > 0:39:03- It changes to be - an incredible rainbow of colours.
0:39:05 > 0:39:10- But only with an ultraviolet torch - can you see these colours.
0:39:12 > 0:39:17- These colours help the algae - during the photosynthesis process.
0:39:32 > 0:39:36- The pigment - which causes the intense colour...
0:39:36 > 0:39:38- ..protects the coral from the sun.
0:39:57 > 0:39:59- You can see immediately...
0:39:59 > 0:40:04- ..that the colours - look very different at night.
0:40:05 > 0:40:08- The red is somehow brighter.
0:40:09 > 0:40:12- The yellows and blues - and all the colours come out.
0:40:12 > 0:40:15- A few fish - are sleeping under the coral.
0:40:23 > 0:40:28- The reef is busy - all day and all night.
0:40:31 > 0:40:34- It's like a 24-hour city.
0:40:39 > 0:40:42- At night, the reef's - a far more dangerous place...
0:40:43 > 0:40:46- ..when the predatory fish - come out to look for food.
0:41:11 > 0:41:14- Here are two fish.
0:41:14 > 0:41:16- The lionfish...
0:41:17 > 0:41:20- ..and the unicorn fish - right in front of me.
0:41:21 > 0:41:23- This is a lionfish.
0:41:23 > 0:41:26- It looks very pretty.
0:41:26 > 0:41:28- But it'd be unwise to pick one up.
0:41:29 > 0:41:34- It has spines along its back, - along the fin...
0:41:34 > 0:41:37- ..which come out on both sides too.
0:41:37 > 0:41:39- It's extremely pretty.
0:41:39 > 0:41:44- The bright colours are there to - warn any other fish not to grab it.
0:41:49 > 0:41:52- You get completely different fish - at night.
0:41:52 > 0:41:56- The fish that were around - during the day are sleeping.
0:41:56 > 0:41:58- They've disappeared.
0:41:58 > 0:42:01- Different fish come out at night.
0:42:27 > 0:42:33- One fish I was very keen to see - was the stonefish.
0:42:33 > 0:42:37- It's one of the most dangerous - and venomous fish in the world.
0:42:40 > 0:42:44- They can weigh up to a kilogram, - and they're very fast.
0:42:50 > 0:42:54- They're usually hard to find - because of their great camouflage.
0:43:01 > 0:43:03- I hope to see one tonight.
0:43:16 > 0:43:21- Here's a fish - I hoped to see at night.
0:43:21 > 0:43:25- I'm not sure if you can make it out.
0:43:25 > 0:43:26- It's moving a little.
0:43:27 > 0:43:30- It's a stonefish.
0:43:31 > 0:43:36- Along its back, it has 13 spines.
0:43:36 > 0:43:39- This one's lying down flat - at the moment.
0:43:39 > 0:43:43- Under each one of those - are two venomous sacs.
0:43:53 > 0:43:57- It's a great experience - seeing the Barrier Reef at night.
0:43:58 > 0:44:01- It's a real honour to be here.
0:44:41 > 0:44:47- But there's something in the back - of my mind that says, "Be careful."
0:44:47 > 0:44:50- You don't know 100% - what's down here.
0:44:50 > 0:44:54- During the day, - you can see all your surroundings.
0:44:55 > 0:44:58- But at night, - it's a different story.
0:44:58 > 0:45:02- All you can see - is this narrow shaft of light.
0:45:48 > 0:45:49- Wow!
0:45:57 > 0:45:59- That was so different.
0:45:59 > 0:46:04- The colours are different at night. - The reds and blues are brighter.
0:46:04 > 0:46:07- The fish are completely different.
0:46:07 > 0:46:09- We saw one stonefish.
0:46:09 > 0:46:13- A big fat lump. Until the lads - pointed it out, I couldn't see it.
0:46:14 > 0:46:16- Its camouflage was perfect.
0:46:16 > 0:46:19- Amazing, interesting - and extremely exciting.
0:46:27 > 0:46:32- The more time I spend diving - and seeing the reef for myself...
0:46:32 > 0:46:35- ..the more I'm starting - to understand the place.
0:46:35 > 0:46:39- I'm seeing some of the secrets - that are out here.
0:46:39 > 0:46:42- It's just a special place.
0:46:42 > 0:46:43- It's so interesting.
0:47:26 > 0:47:28- S4C Subtitles by Testun Cyf.
0:47:29 > 0:47:29