This series is all about wildernesses but can you explain what a wilderness is?

I think everyone's got their own image and definition, or idea of what it is. I would define a wilderness as a place where the impact of humanity is low, and where nature still makes the rules. The entire planet has felt the effects of humans and industrialisation, but the human impact is low in the areas we visit. Nowhere is completely untouched by humanity. There are plastic particles at the bottom of the ocean and the top of Everest, but we were looking for areas where nature was still largely in charge.

Why did you choose to explore the great wildernesses for this series?

I’ve been on dozens of incredible journeys for all my previous series and I’ve seen the huge impact humans have had. But despite it all, there's still a gorgeous Earth out there, a beautiful planet for us to live on and I think I needed a reminder of that, and a lot of people need that reminder as well. For the first time in human history more than half of all people live in urban areas – and in countries like the UK that goes up to more than 80%. We need to remember there’s not just a little patch of Wilderness out there in our big world, there are still huge wild areas of the planet full of mystery and beauty. We all need a bit of a reminder that it’s still out there, that it’s glorious and vital, and that it’s worth caring about and protecting.

Why four episodes in four different wilderness locations?

Wild areas come in all shapes and sizes – hot, cold, mountainous, forest, ocean. The sheer variety of wild landscapes on our planet is mind-blowing and we wanted to get that across to viewers. Each episode is the result of a separate expedition and journey, and the result is four stand alone programmes, each with a different feel.

I travelled to four very different critical ecosystems. Each one overwhelmed my senses with its beauty, the wondrous diversity of life there, the incredible landscapes, and the challenges that are posed by being in wild nature. Even the colours in each wilderness were very different. There's the green of the rainforest in the Congo, the yellow of the Kalahari desert; the white of the Patagonian mountains; and the blue of the Coral Triangle sea. In each contrasting wilderness I encountered completely unique wildlife and met people who have adapted to thrive in the extreme condition.

Was finding the right destinations challenging?

Picking the specific locations was a challenge because we wanted to come up with areas that were different. And then finding the right place that I could go to at the right time of year was tricky as well. Logistically, seasonally, geographically, I was looking for areas that would give people a little bit of a surprise as well.

This series feels quite different to your previous series. Was that part of the plan?

This series is much more global, it's about the whole planet. We're trying to include elements that haven't always been put together in TV programmes - wild areas, but also with landscapes, wildlife, and the human beings who live there as well of course. I'm trying to remind people that we all have a connection to these areas, to Nature – you could call it spiritual. But these are not just nice places to explore and protect. We exist on this planet because these places help to maintain a balance in our ecosystem. You can't have a rainforest the size of the Congo, the second largest tropical forest on the planet, and it not be a fundamental part of our global ecosystem.

If you start to take that away, change will occur. If we want the planet to stay healthy, we need to give a damn about these wild areas, to understand them, learn about them, and then offer nature more focus and protection. By showing and exploring these incredible wilderness areas, I’m hoping to remind and reassure people there’s still time to save them.

The intent around this series was different. We set out here to find remote wild parts of the planet. And it was definitely different to film. These were proper expeditions. They took more time to organise and they were tougher journeys, some of the toughest I’ve ever undertaken, which I hope comes across in the end result.

What about the people you met, living in the wild?

Humans have always lived in wild places, but often they’ve been ignored and their role in protecting and shaping the wilderness forgotten. It was really important we incorporated them and their stories into the programmes.

We met some of the most extraordinary and inspiring people on these journeys and I hope we’ve done them justice.

You’ve said these have been your toughest journeys yet? Explain? And how did you prepare?

Physically, these journeys were really hard and really challenging. I knew they’d be physically tough, so I was running around the wilds of Devon where I live for months beforehand wearing a 15 kilogram weight vest getting into shape. I looked like a lunatic but it had to be done. I was going on a series of very challenging journeys, not just into tricky hot places, but through and across those places or up, in the case of Patagonia, where we had to climb up a couple of thousand meters to the ice field in the middle of the Andes Mountains, carrying heavy packs with our tents, ropes and of course food.

But I really wanted the journeys to be rigorous and tough because that's the only way that we could get to places that are special and genuinely wild. It's easy to turn up to a town somewhere relatively remote, get a taxi to the edge of the wild and then film and we could have made that look pretty convincing. But that’s not real Wilderness. We genuinely did try to go to places we could legitimately say are wild . It involved months of preparation and logistically it involved months of me trotting, jogging and then running around wearing this ludicrous weighted vest to prepare. We had to make sure all our kit was spot on and we had to find decent freeze dried expedition food we could boil-up to eat on the journeys, because a TV crew marches on its stomach just like the military.

There was a lot that could have gone wrong on the journeys, and everybody accepted there were risks involved. We faced challenges along the way and I was quite lucky, really, to emerge from the journeys relatively unscathed. We found a jigger flea burrowing its way into the foot of Jonathan our cameraman, laying its eggs inside him. That had to be dug out with a scalpel by torchlight in the middle of the Congo jungle. Eric, one of the directors, went down with a fever in the middle of the sea in the Coral Triangle off the coast of Indonesia, and we spent a night struggling with maps trying and failing to find anywhere within reach where there was a clinic or potentially somewhere to land a rescue helicopter. Luckily, in the end it wasn’t necessary, but it was a reminder of how incredibly remote we were. And in Patagonia, our cameraman Piers damaged his ankle while we were going up into the Andes, and had to be taken back down. There were a host of physical risks and challenges, of course, not least when I went off into the depths of the Kalahari alone with two local trackers, facing potentially man-eating lions with just a small can of pepper spray strapped to my belt!

What is the one standout moment from the series?

It must have been when I was crawling along the ground with two trackers and hunters in the heart of the Kalahari, trying to get up close to a herd of wildebeest. The guides were trying to feed their families and small village in the wild. As we approached, the hunters popped up and fired off their poison arrows. But because I was with them we weren’t close enough. They missed and the herd stampeded away. That felt as primal as anything I've ever done.

One of the two trackers I was with is called Old Tui, he’s one of the San – the original people of the Kalahari. He was one of the most magnificent humans I've met anywhere in the world and so welcoming. He had a deep Encyclopaedic knowledge of the natural world, like it's hard to find anymore anywhere on planet Earth. He's a master tracker - there are very few of them left out there.

That experience sends a proper shiver down my spine, remembering I've done that. It's an incredible privilege and one which I hope we captured in a way that will resonate with viewers. I hope, as a result of that moment, people watching the programmes will see the struggle of the San to find food and protein, and I hope people will recognise and respect their existence a little more.

What surprised you the most along the way?

I think the people were the surprise. The people we encountered in ludicrously remote parts of the planet were such very strong, fascinating, welcoming characters. They weren't opposed to our presence, they were so pleased to engage with us. You can see in the first episode, for example, one of the Baka people who agreed to carry our camera while he climbed up a tree to harvest wild honey from angry bees and he's telling the other guys to hang on, so he can get a shot of it for the viewers. Their engagement with what we were doing was a big surprise and it showed how magnificent they are. Their incredible lives, their experience, in the wild, in the wilderness, I think, makes them bigger human beings than the rest of us. When we look at people on the planet, our focus is resolutely towards great cities as the places we identify as being the pinnacle of our existence. But actually, these people in the wild are the most sophisticated human beings of all, living in difficult situations but incredibly rich environments .

I met a number of people in these remote places who had grown up on the edge of towns or in cities, and they turned their backs on those lives, because they were seeking a more powerful natural existence. Often they were young guys who had gone into the wild to find themselves and to feel more connected to their planet. I found that fascinating . I really believe we all need the wild in our lives, we need a more profound connection with Mother Nature, and I speak from my own experiences growing up in a grey bit of West London, and finally encountering the wild and feeling the powerful life change it can provide. I saw that same transformation among people we encountered on these journeys.

Is that what motivates you to focus on human stories in relation to nature and destinations?

That chance to interact with people is what I love most about the journeys. It's always the interactions with people that I remember most and I think it’s what I’ll really remember forever when I'm eventually told I've got to hang up my passport. I think we're all fascinated by the lives of other people, and I've been very privileged to meet people on all my journeys with fascinating stories to share.

What have you gained from each series you’ve filmed?

I think every journey has changed me in in some ways and helped me to grow as a person. I flunked out of school without any real qualifications, and these journeys have been part of my college and university. I've stepped out onto the planet with my eyes wide open, with a real willingness to learn. So every journey changes me. Every encounter on these expeditions taught me something and helped show me a totally different side of our world. These journeys reminded me how much glory and beauty there is out there, and the fundamental part humans play in the landscape and ecosystem of the world.

Did you really eat testicles on your travels?

If you're going on a TV journey, you have to do mad things like that. I stayed with Gaucho cowboys on the edge of the South Patagonian icefield in the Andes Mountains, and they eat a diet of a pure carnivore. Testicles are on the menu a lot and they are quite tasty, to be honest. They call them prairie oysters in North America, and they’re a bit like eating a soft-boiled egg.

What's next? Where would you like to travel to on your next adventure?

Honestly, I have no idea. I've got no journeys in the pipeline. Where I would love to go to next, is another matter. I've been on a lot of journeys, but it is an enormous planet out there. It's constantly changing, growing, shaping, developing, and being degraded. Trying to capture, to explore and explain that world, that is one of the greatest honours of my little existence. What makes my journeys fascinating for me on the road is the people I get to meet, and with eight billion of us, that’s an infinite stock of stories to capture. So where's next? I'd love to go to Japan, I would love to travel in West Africa. There are countless more journeys I would love to do. I would love to travel more in Brazil, in Indonesia, in the Philippines. It's an amazing, wonderful world out there and despite making programmes for nearly two decades and having visited more than 100 countries, on six different continents, I feel like I’ve just scratched the surface.