0:00:04 > 0:00:08On Deadly 60, I've had loads of incredible animal encounters.
0:00:08 > 0:00:11Shark! 'Here's one of my many favourites.'
0:00:17 > 0:00:18Today, we're in Borneo,
0:00:18 > 0:00:23hanging out with the Bajau sea gypsies, who live on this island and in the sea around the reef.
0:00:31 > 0:00:34The world beneath their boats is a multi-coloured dream
0:00:34 > 0:00:37of dazzling marine creatures. But for the moment,
0:00:37 > 0:00:41the most fascinating thing to them is our cameras.
0:00:48 > 0:00:51We've had a tip-off. There's one place around here
0:00:51 > 0:00:55that attracts the largest, most powerful predators,
0:00:55 > 0:01:00so that's exactly where we're diving now, to find my next deadly animal.
0:01:00 > 0:01:05It's not far from the reef. In fact, it's the edge of it.
0:01:06 > 0:01:09The reef really feels like home...
0:01:10 > 0:01:14..when just at the end of it you've got this.
0:01:16 > 0:01:18The drop off.
0:01:19 > 0:01:23This is where the reef meets the open ocean.
0:01:27 > 0:01:33The drop off disappears 600 metres straight down into the abyss.
0:01:33 > 0:01:35It gives you vertigo.
0:01:37 > 0:01:39It's like stepping off the edge of a cliff
0:01:39 > 0:01:42with the big blue beneath you.
0:01:43 > 0:01:48There are still plenty of fish here, but they daren't stray too far
0:01:48 > 0:01:53from the wall, because the open ocean is full of lethal killers.
0:01:53 > 0:01:55They're keeping close to the coral,
0:01:55 > 0:02:00cos it keeps them safe from the big fish with the big teeth.
0:02:00 > 0:02:02And then looming out of the deep blue,
0:02:02 > 0:02:05one of the fastest assassins in the sea.
0:02:05 > 0:02:08Steve, check out the fish up above you.
0:02:09 > 0:02:15Dogtooth tuna - with power, speed and sharp teeth, this is the real deal.
0:02:16 > 0:02:19It's swimming straight at our cameraman -
0:02:19 > 0:02:21look at that! Gulping, his mouth open.
0:02:29 > 0:02:32Wonderful stuff!
0:02:32 > 0:02:33I love it!
0:02:40 > 0:02:42Fierce hunters stalk the depths, just waiting
0:02:42 > 0:02:45for a small fish to stray too far from home.
0:02:45 > 0:02:48This is another one of the speed merchants of the sea.
0:02:49 > 0:02:51It's a giant trevally.
0:02:51 > 0:02:54There's another one over there as well.
0:02:55 > 0:02:57Look at the size of them!
0:02:57 > 0:03:00Absolutely huge.
0:03:00 > 0:03:02They're exceptional hunters.
0:03:02 > 0:03:06At the moment, they're just curling along the outside...
0:03:09 > 0:03:12..looking for something to snap up. No way I'm keeping up with them.
0:03:20 > 0:03:25Cruising through crystal seas, the sun cuts down through the blue.
0:03:25 > 0:03:29Then suddenly, it seemed a huge cloud blocked out the sun.
0:03:30 > 0:03:32But it wasn't a cloud.
0:03:32 > 0:03:36It was one of the world's most awe-inspiring wildlife spectacles.
0:03:36 > 0:03:40That is the largest school of barracuda I've ever seen.
0:03:45 > 0:03:49This is absolutely dazzling.
0:03:50 > 0:03:52One of the meanest...
0:03:52 > 0:03:55fastest, fiercest fish in the sea.
0:03:57 > 0:03:59And I've never seen so many of them.
0:03:59 > 0:04:01Ha-ha-ha!
0:04:09 > 0:04:12That is unbelievable!
0:04:13 > 0:04:16Absolutely surrounded by them.
0:04:34 > 0:04:37I've never seen anything like it!
0:04:37 > 0:04:40They're almost surrounding me in a circle.
0:04:44 > 0:04:46Spinning around and around.
0:04:48 > 0:04:51This is absolutely dazzling.
0:05:05 > 0:05:08Barracuda are all about teeth.
0:05:08 > 0:05:12They have two sets - the huge long teeth at the front are used to grab their prey,
0:05:12 > 0:05:15but the real damage is done by the teeth at the back.
0:05:15 > 0:05:19They act like scissors, cutting prey in half in a single bite.
0:05:19 > 0:05:21Even sharks can't do that.
0:05:21 > 0:05:25When you're diving with barracuda, it's wise to keep your hands
0:05:25 > 0:05:28tucked in and don't show off silvery items like watches,
0:05:28 > 0:05:31otherwise they might mistake it for a small fish
0:05:31 > 0:05:34and then you're going to lose your hand.
0:05:34 > 0:05:39Look at them! There are thousands of them!
0:05:42 > 0:05:44I've never seen anything like it!
0:05:47 > 0:05:51Although they look totally effortless in the way they move,
0:05:51 > 0:05:56actually they're really travelling quite fast.
0:05:56 > 0:06:00I'm breathing pretty heavily just keeping up with them.
0:06:04 > 0:06:06Barracuda -
0:06:06 > 0:06:09definitely going on my Deadly 60.
0:06:12 > 0:06:15Hanging around in whirlwind shoals,
0:06:15 > 0:06:18lightning fast with terrifying teeth,
0:06:18 > 0:06:20barracuda are the wolves of the sea.
0:06:20 > 0:06:23and definitely worthy of a spot on my Deadly 60.
0:06:36 > 0:06:39Subtitles by Red Bee Media Ltd
0:06:39 > 0:06:42E-mail subtitling@bbc.co.uk