0:00:03 > 0:00:04My name's Steve Backshall.
0:00:06 > 0:00:10And this is Deadly Pole To Pole.
0:00:10 > 0:00:11Ohhh!
0:00:11 > 0:00:14From the top of the world to the bottom.
0:00:14 > 0:00:15Whoa!
0:00:15 > 0:00:17Deadly places,
0:00:17 > 0:00:19deadly adventures,
0:00:19 > 0:00:20and deadly animals.
0:00:21 > 0:00:24And you're coming with me, every step of the way!
0:00:26 > 0:00:28Arghhhh!
0:00:30 > 0:00:33This time on Deadly Pole to Pole, the team and I have made our way
0:00:33 > 0:00:36to the Bahamas and as you'd expect, from a group of islands surrounded
0:00:36 > 0:00:40by the Caribbean sea, most of this mission is going to be underwater.
0:00:42 > 0:00:46The Bahamas is 4,500 miles from the Arctic Circle
0:00:46 > 0:00:49where our journey began and it couldn't be more different,
0:00:49 > 0:00:54with around 700 tropical islands, surrounded by the Caribbean Sea.
0:00:54 > 0:00:56But we won't be lazing around on beaches,
0:00:56 > 0:00:59instead we're heading beneath the waves.
0:00:59 > 0:01:01We'll be meeting some old friends.
0:01:02 > 0:01:04Wow!
0:01:04 > 0:01:06I'm not comfortable with you at all.
0:01:07 > 0:01:11We'll be using Deadly technology to get a totally new view
0:01:11 > 0:01:12of the ocean's biggest bites...
0:01:15 > 0:01:17..before facing my deepest fears
0:01:17 > 0:01:20in one of the deadliest environments known to man.
0:01:20 > 0:01:23You're underground and underwater
0:01:23 > 0:01:25and a very, very long way from safety.
0:01:29 > 0:01:31There's one group of animals that we come back to
0:01:31 > 0:01:33over and again on Deadly... the sharks.
0:01:35 > 0:01:36Whoa!
0:01:36 > 0:01:39But this time we're aiming to take our understanding of sharks
0:01:39 > 0:01:40to a whole new level.
0:01:44 > 0:01:48Beneath these warm waters is a phenomenal diversity of life
0:01:48 > 0:01:50and particularly sharks.
0:01:50 > 0:01:52There are dozens of different species here,
0:01:52 > 0:01:55from the very small to the very, very big.
0:01:55 > 0:01:58We're here to find out something very special,
0:01:58 > 0:02:01something completely new about the way a shark bites.
0:02:04 > 0:02:08'To do this, we've stacked our boat full of hi tech kit
0:02:08 > 0:02:10'and made our way to shark central.
0:02:10 > 0:02:13'These are lemon sharks, one of the most whippy, bendy,
0:02:13 > 0:02:15'manoeuvrable of all sharks.
0:02:15 > 0:02:18'But how big is a lemon shark's bite?'
0:02:18 > 0:02:21The sharks here are used to being fed
0:02:21 > 0:02:25and the second the boat's turned up, we are surrounded by sharks.
0:02:25 > 0:02:27I mean, already I've lost count.
0:02:27 > 0:02:31There must be 15 animals in the water around us right now.
0:02:31 > 0:02:34'Stage one of our bite analysis is to measure how powerful
0:02:34 > 0:02:37'their jaws are, using a pressure gauge.'
0:02:40 > 0:02:4340 pounds per square inch or thereabouts.
0:02:44 > 0:02:48I'm hoping that our shark is going to be substantially more.
0:02:48 > 0:02:51As you can see, I've tied a bunch of fish to the end,
0:02:51 > 0:02:54now all I need to do is get a shark to bite down there
0:02:54 > 0:02:58and we'll see what force they exert with their jaws.
0:03:00 > 0:03:02In the water.
0:03:02 > 0:03:04Wow!
0:03:04 > 0:03:08'To get an accurate reading we need a strong chomp on the rubber tube.'
0:03:09 > 0:03:12Oh, that's a good bite. That's a good bite.
0:03:20 > 0:03:23That's the...whoa! Oh, no, no, no, no!
0:03:23 > 0:03:24It got my pole!
0:03:27 > 0:03:29Oh, no!
0:03:31 > 0:03:33Who fancies going in and getting it?
0:03:33 > 0:03:35Gone!
0:03:35 > 0:03:39That's our bite test gauge swimming off into the blue.
0:03:39 > 0:03:40It could take a while to find.
0:03:41 > 0:03:45Right, I think we might be moving to Plan B.
0:03:45 > 0:03:48Crazy as it seems, we're getting in there.
0:03:50 > 0:03:53'We want to analyse a shark bite underwater,
0:03:53 > 0:03:56'and the only way to do that, is to feed the sharks by hand.'
0:03:56 > 0:04:00This chainmail is kind of like what a medieval knight would wear
0:04:00 > 0:04:02to go into battle.
0:04:02 > 0:04:04We've got so many sharks here,
0:04:04 > 0:04:07so I kind of feel it's better to be safe than sorry.
0:04:07 > 0:04:10Our aim is to show you the science of a shark bite
0:04:10 > 0:04:12using some Deadly technology.
0:04:12 > 0:04:15We're going to try something a little bit new and very special now.
0:04:15 > 0:04:19We're using this. It's called a time slice rig.
0:04:19 > 0:04:24It has 20 small cameras, all aligned around this semicircle of metal and
0:04:24 > 0:04:29they'll all fire off simultaneously, allowing us to freeze in time
0:04:29 > 0:04:31the exact moment of a shark's bite.
0:04:31 > 0:04:34It'll mean that we can see it in three dimensions,
0:04:34 > 0:04:38understand it in super slow speed and it should
0:04:38 > 0:04:41give us a better understanding of the anatomy of a shark bite.
0:04:44 > 0:04:49'Using the time slice on land would be tricky, but underwater, and
0:04:49 > 0:04:54'surrounded by a shiver of sharks, it'll be a serious challenge.'
0:04:54 > 0:04:57'The first problem is how to get a shark to bite on cue
0:04:57 > 0:04:59'and in exactly the right place,
0:04:59 > 0:05:04'and for that, we have a box load of fish to feed them.
0:05:04 > 0:05:08'Already, they're attracting the interest of dozens of hungry sharks.'
0:05:11 > 0:05:14As these sharks are circling around the bait box,
0:05:14 > 0:05:18it gives me a perfect opportunity
0:05:18 > 0:05:20to show you a bit about their senses.
0:05:21 > 0:05:24So, the eyes...
0:05:24 > 0:05:26..are actually quite small...
0:05:27 > 0:05:29..and it's clear that this species
0:05:29 > 0:05:31really isn't driven by its vision at all.
0:05:33 > 0:05:37But if you look at the head, you'll spot lots of
0:05:37 > 0:05:40tiny, little black dots
0:05:40 > 0:05:42and those are electrical sensors.
0:05:43 > 0:05:46'These work at close quarters, detecting the electrical impulses
0:05:46 > 0:05:49'made by the muscles of their prey as they move.
0:05:49 > 0:05:53'The shark can zone in using just these signals even on prey it
0:05:53 > 0:05:54'can't see.'
0:05:54 > 0:05:57A far more potent sense is its sense of smell.
0:05:58 > 0:06:01So, these sharks have nostrils here.
0:06:02 > 0:06:04They can smell... As you can see, these ones,
0:06:04 > 0:06:08they can clearly smell that there's something inside that box.
0:06:11 > 0:06:14Getting them to bite in just the right spot for the time slice
0:06:14 > 0:06:18will take timing and precision which is going to take practice.
0:06:18 > 0:06:21Hey, I haven't opened it yet. Don't be so impatient.
0:06:25 > 0:06:26OK.
0:06:28 > 0:06:29Here's a likely customer.
0:06:31 > 0:06:32Oh!
0:06:32 > 0:06:34Oops!
0:06:35 > 0:06:36Oh!
0:06:36 > 0:06:38Wow!
0:06:44 > 0:06:47This is absolute craziness.
0:06:49 > 0:06:51Once I'm comfortable with feeding them by hand,
0:06:51 > 0:06:53it's time to try it in the time slice.
0:06:56 > 0:06:58OK, so this is the plan.
0:06:59 > 0:07:03We have our time slice rig lined up here,
0:07:03 > 0:07:05with Johnny and Duncan holding on to it.
0:07:07 > 0:07:11I'm going to try and bring a shark in and get it to bite right dead in
0:07:11 > 0:07:15the centre, so the cameras can fire off all around it
0:07:15 > 0:07:17and then, hopefully,
0:07:17 > 0:07:22we should be able to break down the bite into its constituent parts.
0:07:23 > 0:07:27It might sound easy, but trust me, it's not going to be.
0:07:34 > 0:07:36There are sharks everywhere!
0:07:39 > 0:07:41I'm getting absolutely beaten up here.
0:07:43 > 0:07:47'I need a clean, clear bite, right in the epicentre of the cameras...
0:07:50 > 0:07:52'..while taking care not to get bitten
0:07:52 > 0:07:54'by an overenthusiastic shark.'
0:07:55 > 0:07:57Oh, ow.
0:07:59 > 0:08:04'Despite being super keen to feed, there's no mindless frenzy here.
0:08:04 > 0:08:07'The sharks clearly want to eat the fish, but not us.'
0:08:11 > 0:08:13'Finally, we start to get the hang of it.
0:08:13 > 0:08:15'Our plan is coming together.' Yes!
0:08:19 > 0:08:20Perfect.
0:08:27 > 0:08:29'But with this many excited sharks,
0:08:29 > 0:08:31'you need eyes in the back of your head.'
0:08:33 > 0:08:35Oh...!
0:08:35 > 0:08:36Argh!
0:08:40 > 0:08:44Well, I got pretty hammered there.
0:08:44 > 0:08:47Got a hold of my hand and dragged me off.
0:08:47 > 0:08:48I don't think it meant to bite me.
0:08:48 > 0:08:51I just didn't get my hand out of the way in time
0:08:51 > 0:08:53and it grabbed hold of the fish.
0:08:54 > 0:08:57I'm pretty sure though that we've got our shot now...
0:08:57 > 0:09:02and, actually, the sharks are feeling a little close for comfort,
0:09:02 > 0:09:03so I think it's time to head up.
0:09:05 > 0:09:08The crew have downloaded the time slice footage.
0:09:08 > 0:09:10Let's see what it reveals.
0:09:10 > 0:09:12OK, so...
0:09:12 > 0:09:14..you can see the lemon shark coming in here.
0:09:15 > 0:09:18Oh, wow!
0:09:20 > 0:09:22That is incredible!
0:09:23 > 0:09:25Fantastic.
0:09:27 > 0:09:31The time slice has captured the exact moment of the strike.
0:09:31 > 0:09:33It allows us to analyse the bite from every angle.
0:09:35 > 0:09:38Now, because the mouth is on the underside of the head,
0:09:38 > 0:09:41it needs to lift the nose up quite considerably to be able to
0:09:41 > 0:09:43stand any chance of getting a bite.
0:09:47 > 0:09:49But the jaws are very, very different
0:09:49 > 0:09:51to the jaws that you'd see in a mammal.
0:09:51 > 0:09:54We have our upper jaw fused to our skull
0:09:54 > 0:09:56and only our lower jaw can move free.
0:09:56 > 0:09:58In a shark it's completely different.
0:09:59 > 0:10:03And you can see that at this moment of the strike.
0:10:04 > 0:10:06There.
0:10:06 > 0:10:09Both the shark's upper and lower jaws thrust forward.
0:10:09 > 0:10:14Rows of fish-hook thin pointed teeth can snag larger prey.
0:10:14 > 0:10:16Smaller prey is just hoovered up.
0:10:19 > 0:10:22Its huge gaping mouth creates a massive cavern
0:10:22 > 0:10:25and water is sucked in like a vacuum, along with food.
0:10:28 > 0:10:29Look at that!
0:10:29 > 0:10:32It's sucked down a whole fish right in front of us.
0:10:36 > 0:10:40Well, the chainmail certainly did its job and with results like these,
0:10:40 > 0:10:45I can't help hopping back in for one last slice of lemon shark action.
0:11:10 > 0:11:11Um...!
0:11:11 > 0:11:15I think we've got a bit too many sharks for this.
0:11:15 > 0:11:16Argh!
0:11:21 > 0:11:24With a suite of super senses to find prey.
0:11:24 > 0:11:27Their rows of thin, pointy teeth snag into fish
0:11:27 > 0:11:31and their bite could swallow a beach ball.
0:11:31 > 0:11:33Lemon sharks are a formidable,
0:11:33 > 0:11:34fish munching machine with
0:11:34 > 0:11:35jaws for the job.
0:11:39 > 0:11:41MUSIC: TITANIC THEME TUNE
0:11:44 > 0:11:49Seriously, my next deadly contender is another Caribbean shark,
0:11:49 > 0:11:51but this is a very different beast.
0:11:52 > 0:11:56It's the Bahamas' largest and most feared predator...
0:11:57 > 0:11:59..the tiger shark.
0:12:00 > 0:12:02They can get to be as long as a limousine,
0:12:02 > 0:12:06weigh the same as a small car, have an intimidating reputation
0:12:06 > 0:12:09and this could be the best place on Earth to find one.
0:12:13 > 0:12:17So, this is Tiger beach, except there's no beach
0:12:17 > 0:12:19and no tigers either.
0:12:19 > 0:12:21Well, not the obvious kind, anyhow.
0:12:21 > 0:12:24In actual fact, it's a shallow sandbank, surrounded by miles
0:12:24 > 0:12:26and miles of open sea.
0:12:27 > 0:12:28We're hoping for a dark
0:12:28 > 0:12:30and distinctive silhouette under the water.
0:12:32 > 0:12:33But, at the moment, all we can see
0:12:33 > 0:12:36are our old friends the lemon sharks.
0:12:36 > 0:12:38But we're making sure we're ready.
0:12:42 > 0:12:46And a big tiger shark has teeth
0:12:46 > 0:12:49and bite force that can get through the shell of a turtle.
0:12:49 > 0:12:50So, this...
0:12:50 > 0:12:54well, I think it's more for my peace of mind than anything else.
0:12:55 > 0:12:59Got something coming back. I don't know if it's a tiger now.
0:12:59 > 0:13:01Big dark spot coming in right now.
0:13:02 > 0:13:03Could be.
0:13:03 > 0:13:06Could be the tiger coming in now. I don't know.
0:13:08 > 0:13:11'We're not sure, but we're going to get in to check it out.'
0:13:15 > 0:13:18Tiger sharks are opportunists and omnivores,
0:13:18 > 0:13:21which means they'll eat almost anything that come their way.
0:13:21 > 0:13:25Attacks on humans are incredibly rare but we need to be
0:13:25 > 0:13:28super vigilant for anything that doesn't look like a lemon shark.
0:13:31 > 0:13:35So far, all I can see are lemon sharks.
0:13:37 > 0:13:40'But, somewhere out there, a tiger might be circling.'
0:13:49 > 0:13:51Oh, my goodness.
0:13:53 > 0:13:57Well, THIS is why we came here to Tiger beach!
0:13:58 > 0:14:00It's a true monster of a tiger shark.
0:14:03 > 0:14:06It's easy to tell them apart from the lemons.
0:14:07 > 0:14:12The tiger shark is noticeably broader and stouter.
0:14:14 > 0:14:15The eyes are black...
0:14:16 > 0:14:20..and it has these stripes and dappling colouration
0:14:20 > 0:14:21running down the sides...
0:14:22 > 0:14:24..that give it its tiger name.
0:14:25 > 0:14:27It's a much more menacing shark.
0:14:31 > 0:14:35It's one of the largest purely predatory creatures on Earth.
0:14:36 > 0:14:41They're well-known for taking just about anything
0:14:41 > 0:14:42they can fit into their mouths.
0:14:45 > 0:14:48The teeth are also totally different to the lemons -
0:14:48 > 0:14:51short, wide, curved and with a serrated edge,
0:14:51 > 0:14:54they can carve through turtle shells, sea birds
0:14:54 > 0:14:57even other sharks, they're not fussy.
0:14:57 > 0:15:01They've even been known to eat car tyres and number plates.
0:15:01 > 0:15:04They cruise up and down in the water column using smell
0:15:04 > 0:15:05to hone in on food.
0:15:07 > 0:15:12So, now we have two tiger sharks in the mix
0:15:12 > 0:15:15and that's completely changed the situation. Three?!
0:15:16 > 0:15:19Yes, another one. Whoa.
0:15:19 > 0:15:23Right, from here on in, we're going to have to be much more careful.
0:15:25 > 0:15:27A lemon shark could give you a nasty nip...
0:15:28 > 0:15:33..but, if a tiger shark got a hold of you, even wearing a chainmail...
0:15:33 > 0:15:35it's going to be very bad indeed.
0:15:35 > 0:15:39I'm...I'm really nervous about this tiger here, it's a bit...
0:15:39 > 0:15:41a bit too...
0:15:41 > 0:15:43aggressive for my liking, actually.
0:15:45 > 0:15:46It really...
0:15:48 > 0:15:50..that one there, it's got attitude.
0:15:52 > 0:15:55The other ones I'm fine with, but that one, that needs to be watched.
0:15:57 > 0:16:01I'm not comfortable with you at all.
0:16:02 > 0:16:03Whoa!
0:16:04 > 0:16:06Do you know what?
0:16:07 > 0:16:10This shark is not good.
0:16:12 > 0:16:16'It's instantly obvious that every shark has a different personality.
0:16:16 > 0:16:20'This one is bold, confident and inquisitive, and,
0:16:20 > 0:16:22'as sharks don't have hands to feel with,
0:16:22 > 0:16:24'they use their mouths and their teeth.'
0:16:26 > 0:16:28I've got my eye on you.
0:16:34 > 0:16:36This is absolute chaos!
0:16:40 > 0:16:42There - on your fin, Si. No, draw in your foot.
0:16:42 > 0:16:43Draw in your foot, seriously.
0:16:43 > 0:16:45Whoa, whoa, whoa! Si, Si, Si!
0:16:50 > 0:16:52Everyone OK down there?
0:16:54 > 0:16:57That shark very, very nearly took a bite of Simon's leg...
0:16:59 > 0:17:01..and that's a tiger, that's not good news.
0:17:02 > 0:17:07'Best not to overstay our welcome. This is the tiger sharks' domain.
0:17:07 > 0:17:10'These awe-inspiring beasts are the true lords of
0:17:10 > 0:17:14'the Caribbean seas - we are merely visitors.'
0:17:14 > 0:17:16That was really hard work.
0:17:16 > 0:17:20There were a lot of tigers around.
0:17:20 > 0:17:22It's impossible to keep your eyes on all of them,
0:17:22 > 0:17:24so, just when you think you've got it sussed
0:17:24 > 0:17:26and you know where they're coming from,
0:17:26 > 0:17:29another one'll come and hammer you from...from behind.
0:17:34 > 0:17:35They can weigh over half a ton.
0:17:38 > 0:17:40And can bite through a turtle's shell.
0:17:42 > 0:17:45With pugnacious personality...
0:17:45 > 0:17:46tiger sharks are the Caribbean's
0:17:46 > 0:17:48ultimate underwater predator.
0:17:55 > 0:17:58'I'm continuing my search for the Bahamas' most deadly
0:17:58 > 0:18:01'by heading inland because there is something here
0:18:01 > 0:18:05'that's, to me, more terrifying than any tiger shark.'
0:18:05 > 0:18:09What lies ahead is one of the most challenging, certainly for me,
0:18:09 > 0:18:11the most frightening thing that we've ever done on Deadly.
0:18:13 > 0:18:17For once, this is not a deadly animal, it's a deadly place.
0:18:19 > 0:18:23Over the years I've done expeditions in every kind of environment -
0:18:23 > 0:18:25mountains, desert, arctic.
0:18:25 > 0:18:29But there's one that scares me more than any other, it's caves.
0:18:29 > 0:18:32And if there's one thing that's more frightening than a cave,
0:18:32 > 0:18:35it's a flooded cave that has absolutely no air in it.
0:18:37 > 0:18:40'It may appear to be an innocent looking forest pool,
0:18:40 > 0:18:45'but it's actually the gateway to a mysterious underworld.'
0:18:49 > 0:18:52Peppered around the Caribbean, these pools mark the entrance to
0:18:52 > 0:18:53flooded passages and caves,
0:18:53 > 0:18:56stretching for hundreds of miles underground.
0:18:58 > 0:19:02They are some of the most beautiful and unexplored places on Earth,
0:19:02 > 0:19:05but have the potential to be lethal.
0:19:06 > 0:19:08If you lose your way in these labyrinths,
0:19:08 > 0:19:10you won't be coming out alive.
0:19:14 > 0:19:17So, back in the UK I've been training hard to prepare.
0:19:17 > 0:19:21Cave diving requires a specialist set of skills and nerves of steel.
0:19:28 > 0:19:32'It's dark, claustrophobic and requires a lot of experience
0:19:32 > 0:19:33'and technical knowledge.'
0:19:33 > 0:19:37Here's hoping the Bahamas is going to be somewhat different.
0:19:38 > 0:19:41'At least here I'm good hands,
0:19:41 > 0:19:43'as I've teamed up with some elite cave divers.'
0:19:45 > 0:19:47Flooded caves are one of the most unexplored environments
0:19:47 > 0:19:50on the planet, but they're also one of the most dangerous and
0:19:50 > 0:19:53one of the reasons for that is there's no air inside them.
0:19:53 > 0:19:55If you're diving out in the sea and something goes wrong, you can
0:19:55 > 0:19:57come to the surface. You can't in a cave.
0:19:57 > 0:20:00So, we've got enormous amounts of compressed air.
0:20:01 > 0:20:05The other complete nightmare with cave diving would be
0:20:05 > 0:20:08if everything went dark because then you'd get lost
0:20:08 > 0:20:10and if you get lost, you're probably not going to come out alive.
0:20:10 > 0:20:13So, I've got an awful lot of light.
0:20:15 > 0:20:17'Whenever I get into a cave, I start feeling claustrophobic
0:20:17 > 0:20:21'and I can feel my heart rate going up and it does really frighten me.'
0:20:21 > 0:20:24When you're diving that is the last thing you want.
0:20:24 > 0:20:26If your heart rate goes up, then your breathing goes up
0:20:26 > 0:20:28and you start using up much more air,
0:20:28 > 0:20:32so you want to relax, you want to calm yourself down.
0:20:32 > 0:20:34Can't put it off any longer.
0:20:43 > 0:20:45Over all the years that Johnny the cameraman and I have been
0:20:45 > 0:20:48working together, we've done all sorts of dives -
0:20:48 > 0:20:50sharks, whales, crocodiles.
0:20:50 > 0:20:54This is the first time that he's not allowed to come with me.
0:20:54 > 0:20:56'I'm just praying this is all going to be worth it.'
0:21:00 > 0:21:03At the moment, all I'm doing is shaking with fear.
0:21:04 > 0:21:06'The other cave divers will be watching my back
0:21:06 > 0:21:09'and also filming what we find.
0:21:09 > 0:21:11'It's time to leave my crew behind.'
0:21:18 > 0:21:21Three...two...one.
0:21:30 > 0:21:32'The darkness is so disorientating,
0:21:32 > 0:21:35'it's hard to know which way is up or down.'
0:21:43 > 0:21:46'But as I get my bearings, we make our first discovery.'
0:21:49 > 0:21:51Amazing!
0:21:52 > 0:21:54Well...
0:21:55 > 0:21:59..there's not much life living in these caves,
0:21:59 > 0:22:00but there are a few...
0:22:02 > 0:22:04..creatures that make their home here.
0:22:04 > 0:22:07Like these...tiny shrimp.
0:22:09 > 0:22:12Look at all of the long antennae that it's tapping around
0:22:12 > 0:22:15in the darkness with. It can't see...
0:22:16 > 0:22:21..so it needs to make best use of those long sensory appendages.
0:22:24 > 0:22:27'This cave shrimp is a rare find.
0:22:27 > 0:22:30'They survive here by feeling their way with tactile antennae,
0:22:30 > 0:22:33'sensing food and evading predators in the pitch black.'
0:22:36 > 0:22:39So, did you see how fast that swam away?
0:22:41 > 0:22:45'A little deeper in the cave is a truly prehistoric find.'
0:22:48 > 0:22:50This strange fish...
0:22:50 > 0:22:52..it's called a brotula.
0:22:53 > 0:22:57Look at the wonderful way it moves with the undulations of its tail.
0:22:59 > 0:23:04The extraordinary thing is, these fish are predatory,
0:23:04 > 0:23:06so they'll swallow just about anything.
0:23:07 > 0:23:09They're very, very primitive fish,
0:23:09 > 0:23:12they've probably been around on the planet for tens,
0:23:12 > 0:23:15maybe even hundreds of millions of years,
0:23:15 > 0:23:18and remain pretty much unchanged.
0:23:19 > 0:23:24And the only place they live is in caves like this.
0:23:26 > 0:23:29That is one of the weirdest things I've ever seen.
0:23:37 > 0:23:39'Further into the cave system, the water clears,
0:23:39 > 0:23:42'and a world of wonder emerges.'
0:23:52 > 0:23:53No way!
0:23:59 > 0:24:00That is incredible!
0:24:06 > 0:24:09This place is awe-inspiring.
0:24:09 > 0:24:12I've never seen anything like it in my life.
0:24:16 > 0:24:21Even more so because so few people will ever have seen it before.
0:24:26 > 0:24:28I'm having to concentrate...
0:24:29 > 0:24:31..to keep my breathing down...
0:24:31 > 0:24:33and stop my heart rate going up.
0:24:39 > 0:24:42'This cavern is adorned with stalagmites and stalactites
0:24:42 > 0:24:46'that were formed thousands of years ago before the cave flooded.'
0:24:49 > 0:24:53Some of the formations here in the cave are formed of
0:24:53 > 0:24:55all kinds of crystals.
0:24:57 > 0:25:00Look at that - it's just glowing!
0:25:00 > 0:25:04I've never felt more like a visitor to an alien planet than I do here.
0:25:15 > 0:25:18It's easy to be so overwhelmed
0:25:18 > 0:25:20by the beauty and the majesty
0:25:20 > 0:25:23of all the features in these caverns
0:25:23 > 0:25:26that you totally forget where you are
0:25:26 > 0:25:29and, all of a sudden, you remember
0:25:29 > 0:25:31that you're underground and underwater
0:25:31 > 0:25:34and a very, very long way from safety.
0:25:37 > 0:25:39'We've now ventured so deep into the cave
0:25:39 > 0:25:41'that there would be no chance of rescue.'
0:25:44 > 0:25:46'It would be all too easy to get lost,
0:25:46 > 0:25:48'it's a maze of tunnels and dead ends.
0:25:48 > 0:25:52'If I panic or make a mistake now, this could be my watery tomb.'
0:25:57 > 0:25:59'And as if to remind me,
0:25:59 > 0:26:03'we find the remains of a long dead deadly animal.'
0:26:03 > 0:26:05This is certainly...
0:26:05 > 0:26:08not something you expect to see...
0:26:08 > 0:26:10in a cave like this.
0:26:11 > 0:26:13It's the remains of a crocodile.
0:26:14 > 0:26:18This has probably come from about 800 to
0:26:18 > 0:26:204,000 years ago.
0:26:22 > 0:26:24You can still see the upper jawbone...
0:26:26 > 0:26:27..some of the teeth.
0:26:27 > 0:26:30Actually, it's still in remarkably good condition.
0:26:39 > 0:26:41'Places like this are living time capsules of what
0:26:41 > 0:26:44'life was like thousands of years ago.
0:26:44 > 0:26:45'It's hard to tear myself away,
0:26:45 > 0:26:49'but with air supplies running low we have to head for the surface.'
0:26:53 > 0:26:55There's no doubt that caves,
0:26:55 > 0:26:59particularly flooded caves like this are a deadly environment.
0:26:59 > 0:27:02I mean, there's very little margin for error. You get things wrong
0:27:02 > 0:27:05and you haven't really got a lot of chance of surviving.
0:27:05 > 0:27:07But they've got to be one of the most
0:27:07 > 0:27:11magical, mystical places on the planet...
0:27:11 > 0:27:13..and, uh...
0:27:13 > 0:27:15I'm not going to forget that in a hurry.
0:27:16 > 0:27:19Miles of unexplored passages with no air...
0:27:21 > 0:27:23..tight claustrophobic squeezes...
0:27:25 > 0:27:27..and perpetual darkness...
0:27:29 > 0:27:31..make this Bahamas flooded cave
0:27:31 > 0:27:32one of the deadliest places
0:27:32 > 0:27:34I will ever set eyes on.
0:27:36 > 0:27:40Join me next time as I continue my journey on Deadly Pole to Pole.
0:27:42 > 0:27:44Argh!