Orla Doherty, producer of The Deep and Our Blue Planet

I’ve spent more than 500 hours in submersibles 1,000 metres under the sea – the maximum depth technology can take us. You can’t go to the toilet the whole time you’re down there, so you have to hold it for 10 hours. The comms come and go, too. You’d always rather be in constant radio contact – it’s not great when somebody goes quiet. But I’ve spent long enough down there to not get flustered, and to keep faith. Most people say they could never go down in a sub, but it doesn’t bother me at all. If someone could figure out how to make a submarine I could live in and just drive around on the sea floor, I would.

Facebook Twitter Pinterest ‘It’s the absolute final frontier’ … the Blue Planet II. Photograph: Luis Lamar/BBC

Only three humans have ever gone deeper into the trenches, and touched down at the bottom of the ocean: two guys in the 1960s, Don Walsh and Jacques Piccard, then James Cameron. That’s the absolute final frontier. It’s so tantalising. I want to go to the next level, then the next, because there’s still so much we don’t know.

The most exciting thing happened on our very first dive in Antarctica. It was far colder than most of our deep dives, -1.8C (38F), and we knew the sub would react differently. Then we noticed water gathering in the bottom. We were 450 metres deep, so it was 45 minutes back up to the surface. There were three of us down there – the pilot, cameraman and myself – and it was my call what to do.

All sorts of things go through your mind – there’s a giant crack and it’s just going to go. There isn’t a way out. There’s no happy ending. It took 20 minutes to figure out where the water was coming from, and how to stop it getting in. That was an exciting 20 minutes.

The pilot noticed one of the inlets on a pressure gauge wasn’t quite watertight. So it was a seep, not a crack or hole that could rupture, and it was just a case of sealing it off. The pilot asked if I wanted to go straight back to the surface now and I said “No, let’s stay down and get on with our day’s work!” Every single dive into the deep is a precious thing.

Facebook Twitter Pinterest On the attack … Humboldt squid off the coast of Chile. Photograph: Alucia Productions

It’s like all the sci-fi films you’ve ever watched rolled into one. We filmed things nobody has ever seen before and may never see the likes of again. We’ve always known the deep is full of aliens and weird animals with crazy adaptations and bizarre landscapes, but we found more types of coral down there than on shallow tropical reefs. Not just boring white coral either, but also stunning pink ones, purple ones, blue ones. We saw Humboldt squid on the attack, which no one has filmed before. These are two-metre monsters, fierce voracious predators, and we were surrounded by a squadron of a thousand of them. We even saw their far darker side, when they turn on each other and become cannibals if there’s not enough food.

And we found an erupting underwater volcano that was like landing on another planet – these giant bubbles of methane the size of basketballs were shooting out of what looked like an empty seabed. When I showed the scientist who’d told me about these “little bubbles” of gas, she could not believe it. But now, everyone can see it. Interview by Kate Abbott

Jonathan Smith, producer of One Ocean and Coral Reefs

I’ve worked with sharks and orca and whales for years, but the sheer wild brutality of a walrus is the most terrifying thing. When you see them in a colony, they are so aggressive, pushing each other off ice floes and ramming each other with those huge tusks.

But these creatures are also the most tender, loving animals I’ve ever encountered. We saw a mum doing everything she could to keep her pup on an iceberg, and we saw them kissing with their whiskers. They are so chunky and blubbery that they can’t feel through their skin – they use whiskers to feel and touch instead.

Facebook Twitter Pinterest “Three weeks in we were ready to give up’ … a scientist using a hydrophone to record sounds of the reef. Photograph: Roger Munns/BBC Natural History Unit

In the Arctic we filmed much further than any film crew has before in search of walrus on the ever-retreating ice. We were living and working on a bigger boat, then decamping into a small aluminium boat to get closer. The little boat was fitted with an incredibly specialist bit of kit called a Cineflex Heligimbal – a camera developed by the military that normally hangs below helicopters, but we used it to shoot right at water level to get a walrus-eye view. We could be hundreds of metres away but still filming without impacting on them.

The cameraman was stung by a stonefish. We had to get out as fast as we could. I've never seen anyone in so much pain

One day, though, the walrus took an interest in us. We were swarmed. About 50 of them came to about two metres away from us. They were very noisy, and you could certainly smell them. We couldn’t move because they would have got scared. So we’re all sitting there, dead still, with only the cameraman, Ted Giffords, rotating the lens.

Suddenly one of them took a dislike to our camera. Now, this camera is weatherproof and windproof and can handle flying under a helicopter at 100mph – but it’s never been tested as to whether it’s walrus-proof. This mum with big old tusks saw herself in the lens, spied another walrus the same size, and fronted up. Looking through my viewfinder, I saw her walrus getting bigger and bigger, then she reared up and, sure enough, tusked with full force. With lightning speed, Ted managed to move it just enough so she didn’t hit the lens and caught the side instead. We heard this mighty crack, then saw there were these two perfect tusk-like dents in the side of the camera.

Facebook Twitter Pinterest Tender and terrifying … a walrus mother and calf in Svalbard, Norway, from Blue Planet II. Photograph: Jonathan Smith/BBC

My biggest worries on shoots are always around diving. You have to be constantly cautious. No one on my Blue Planet II shoots got the bends, but one cameraman was stung by a stonefish while we were filming Reefs. Roger and I were shooting clownfish, and a stonefish was completely hidden in the sand. He put his finger into the sand to steady himself. He instantly handed me the camera and I could see this tiny prick of blood on the end of his fingertip. That was it. We had to get out as fast as we could. I’ve never seen anyone in so much pain so quickly in my life.

If we’d been down at 20 metres we couldn’t have reached the surface for two hours: you can’t race to the top because that’s what’ll kill you. Luckily we were only 10 metres down. Again luckily, we had boiling water on our boat and we knew their poison is protein-based, so we had to get heat on it as soon as possible – as hot as he could handle for as long as possible. Even with that “instant remedy”, his finger was black for weeks. Interview by KA

Yoland Bosiger, researcher on Green Seas

One of the most incredible creatures I was lucky enough to see was the giant cuttlefish, which aggregate in their hundreds of thousands off south Australia. The males have a number of different strategies that they use to try to win over the females. It was an amazing experience – like watching an underwater soap opera.



We were looking for tuna when our guide got a fishhook in his eye

When you’re down there for four hours at a time it can get pretty chilly. Towards the end of each dive I was getting quite numb. Often they had to push me into the boat because my limbs had seized up. We use a suit called a drysuit, which means no water gets in and you stay as warm as possible. But it creates a bit of a problem if you want to go to the bathroom. I had to buy some adult nappies, which was not particularly fun. Interview by Sam Richards

Facebook Twitter Pinterest ‘When they’re flying at you it’s hard not to get a bit nervous’ … mobula rays. Photograph: Erika Higuera/BBC

Mark Brownlow, series producer

The big blue refers to these vast expanses of ocean that have virtually no life in them at all – they’re like underwater deserts. The sea often has a green tinge from all of the algae within it, but these parts have no nutrients at all.

Nonetheless, we’d heard about feeding frenzies that occur in remote spots. Super-pods of dolphins would gather, and tuna fish would rapidly rise to the surface, to feed on lanternfish. Not many people have heard of lanternfish, but they’re the second most numerous fish on the planet. Fisherman who’d seen the feedings talked about a glorious spectacle and referred to it as “the boiling sea” – so we were desperate to capture it.

We started out near Cairns in Queensland, Australia. We were relying on tuna fishermen to help guide us. Unfortunately, one of our main contacts got a fishhook through his eye and had to go home, which was a major blow for our navigation.

Facebook Twitter Pinterest On the menu … a coral grouper fish. Photograph: Alamy

We spent two weeks out in the ocean and found nothing. But it was the start of El Niño, and that explained why we hadn’t found anything. It doesn’t matter if there have been consistent patterns of life in the ocean for decades, even a small change in the ocean temperature can have a drastic effect.

We ended up filming off the coast of Costa Rica, and this time we took a helicopter. It was pure euphoria when we found what we were looking for – and exactly like the fisherman had said: the tuna fly up to the surface of the water at up to 40mph, and the activity on the surface makes the water look as if it’s boiling. This kind of work is not like swimming with sharks, but there still hairy moments. When you have tuna flying past your head, or two-metre-wide mobula rays it’s hard not to get a bit nervous. Ultimately, though, you realise these creatures know exactly what they’re doing and are not planning on coming into contact with you.

As it’s happening, you feel immense relief that you’ve managed to get the footage you came for. There’s constant pressure doing this job – going home with no footage and a big hole in your budget is not ideal. Of course, there’s a sense of awe that you’re getting to watch this incredible event, something very few people ever get to see first-hand. Although you only enjoy that retrospectively, once you know the footage has actually been recorded. Interview by Tim Jonze

Facebook Twitter Pinterest The fish that hates water … a Pacific leaping blenny Guam. Photograph: Alucia Productions

Miles Barton, producer of Coasts

We filmed in at least 12 countries, from the Seychelles to Brazil, Australia to Norway, but for me the most extraordinary thing that happened was on the Pacific island of Guam – we’re talking 18 hours minimum to fly there – filming a tiny fish that spends all of its adult life on land. It’s a fish that hates water.

The Pacific leaping blenny is the most bizarre example of an animal that operates in two worlds, in sea and on land. They’re three inches long and they look like drab little rocks until a wave comes in – when they all jump in the opposite direction to avoid the water.

Our cameraman, Rod Clarke, who specialises in filming tiny things, would sit on a little fisherman’s stool, up to his waist in the water, with waves crashing around him, balancing £40,000 worth of camera and just a plastic bag over the top. Every now and then I’d have to scream ‘WAVE!’ and he’d leap up, grab the camera and hoik it above his head. It was an absurd situation, as if people were throwing buckets of water at him all the time.

Facebook Twitter Pinterest Filming in 12 countries from the Seychelles and Brazil to Vancouver Island, Canada … ochre seastars. Photograph: Paul Williams/BBC

Blennies come to the tideline to feed on algae, and you can’t see how they steer clear of the water unless you film in extreme slow-motion. They have a completely different style of locomotion to any other animal: instead of walking or using any limbsthey curl their tails against a rock and use them as a spring to leap. They look like little missiles flying through the air.

Nobody has filmed this in the wild before – because it’s just so difficult. It’s more rare these days, filming something that’s never been shown before, but thankfully it does still happen.

We were out there for three weeks, and we almost gave up. Some days either nothing happened or we got the tides wrong. It’s extremely frustrating. When the blennies flick you can’t see it with the naked eye, so sometimes you’d think you got nothing all day, then review the footage and find something spectacular. In one amazing moment, all the fish jump, there’s a pause and then the last one comes flying across the middle of the screen. For me, bringing to people’s attention a charming little fish that does something so special is the most triumphant thing. Interview by KA

Rachel Butler, assistant producer on Ocean and Coral Reefs

We were 30 metres underwater at the sharkiest reef in the world, wearing helmets and body armour, when a dense mass of circling sharks, some 700 in all, brushed against us in the swirling current. The reef was in the pristine waters of French Polynesia, 4,000 miles from the nearest continent. Above us in the boat, staff drilled in evacuation procedures were ready with tourniquets and blood-clotting devices. Someone had died at this reef the week before. They had gone missing after going solo diving.

Facebook Twitter Pinterest ‘The deep is full of aliens’ … a fangtooth. Photograph: Espen Rekdal/BBC

Our aim was to film marbled groupers who gather at the reef to spawn. There were 20,000 of them, and that attracts a huge number of predators, in particular grey reef sharks. These are pretty chunky creatures, about two metres long. They don’t look like great whites but they can be aggressive – and they have 300 extremely sharp teeth.

By day, the sharks are relatively benign. They come into the reef to get cleaned by parasites. But by night, they are completely different animals: they hunt. It’s like that bit in Finding Nemo when a great white scents blood and suddenly turns on Nemo bellowing: “I’m having FISH tonight!” Unfortunately for us, the spawning took place at night, though luckily there was a full moon and clear skies so we didn’t need too much lighting.

It was a daunting experience for many reasons. Sharks have a sixth sense: the electroreception around their snouts is so sensitive it can pick up the faintest electrical stimulus given off by, say, the racing heartbeat of a fish – or a human. Had any of my crew been attacked, it could have been catastrophic, because this was such a remote spot. We were a good six hours from proper medical help.

Facebook Twitter Pinterest Feeding frenzy … reef sharks in Blue Planet II. Photograph: Dan Beecham/Alucia Productions

The sharks attacked the groupers incredibly fast. We had to use high-speed cameras – you can hardly see it with the naked eye. Only when we played back the footage did we really understand the speed at which they moved. It was very hard to watch – we’d spent three weeks following these incredible groupers on their journey to the reef.

Blue Planet 2: Attenborough defends shots filmed in studio Read more

To get in really close, we wore closed-circuit re-breathers that allow you to stay underwater for up to four hours, making no disturbing bubbles. One shark scraped my wrist just by brushing against me. Their skin is actually made up of teeth, developed teeth, so if one rubs against you it’s like sandpaper.

I won’t lie – it was terrifying, even though I knew, as a marine biologist, that we weren’t on the menu, not with all of these grouper around. Even if a shark had drawn human blood it would have been unlikely to trigger a feeding frenzy. They like fish, not us. Still, it’s hard to convince yourself in the moment.

The current was so strong, we had to kick against it the whole time. That was a huge worry. When he came to the surface, my cameraman said: “It was like trying to run a marathon with 100 sharks on your tail.” Personally, I was more scared the time we went to the Galápagos Islands and a pelican got in my tent. Give me sharks any day. Interview by Andrew Gilchrist

• Blue Planet II begins at 8pm on 29 October on BBC1.