Steve Backshall: The adventurer on swimming with great whites, holding a gorilla by the hand, and his failed relationships

I yearn for the golden era of exploration I'd have given anything to have been around when we were truly opening up parts of the planet for the first time. For me, reading what [the British explorer] Alfred Russel Wallace wrote about travelling through the Malay archipelago in the 19th century, when he was discovering new species every single day, it felt like he was having the sort of adventures that, if you'd read about them in King Solomon's Mines, you wouldn't have believed them.

I feel ill at ease in big cities There's nowhere I feel more intimidated than wandering about in town on a Saturday night after chucking-out time, with hammered people rolling round the street. I feel much more at home in the Arctic or up a big mountain. I love that sense of wilderness, of being on my own.

Humans are so much more frightening than animals Animals would rather get away from you than risk conflict in almost every situation. My hairiest experiences have been with humans: when I was working in East Timor in the mid-1990s, writing a guide to the area, I got caught up in cross-fire when a peaceful demonstration was put down with bullets by the military. People were lying in the gutter everywhere; the front of the building I was cowering in was blown away. It was a terrifying experience.

Being hunted by a polar bear was a chilling moment, mind They're one of the few animals on Earth that, given the chance, will stalk, kill and eat a human being. I was on my own [filming], well inside the Arctic Circle up among the pack ice, and a long way from the main boat, when I spotted one. I thought he'd swim on past me, but when he got within 30 metres, he started to approach, keeping icebergs between me and him so I couldn't see him, before ducking underneath one and popping up four metres away. But I was in a modern sea kayak, so I got away.

People think it's lunacy to swim with sharks without a cage [Backshall accompanied a group of great whites while filming Swimming with Monsters.] But it's not suicide, as I know how these animals are likely to act and I do a full risk assessment with every encounter.

Watching mountain gorillas moved me to tears It happened the first time we filmed in Uganda, where we were allowed to spend an hour with them. When the time was up and I stepped away, this tiny baby gorilla, which would have fitted in my hands, fixed its gaze on me from about 20 metres away, then walked with purpose right up to me and sat down practically in my lap, taking me by the hand. I burst into tears.

I've sacrificed a normal life I come from a very close family and I'd always assumed I'd be married with kids by the time I was in my mid-twenties. But I turned 40 last year, I'm single and I have no kids, as I've not been able to hold down a relationship in years. How could I? Last year I was away for nearly 11 months, totally out of contact, so that part of my life has had to take a back seat. I do regret it, though, as I'm at the age when I'm wondering where [a family] is going to come from.

Existential angst sets in after a big trip away One moment you're diving with sea lions, then you're back home dealing with a collapsed drain. So while I look forward to coming home, once back I do sometimes have moments of feeling numb.

Backshall, 40, is an adventurer and TV presenter best known for his children's natural-history series 'Deadly 60'. The new series, 'Deadly on a Mission', which sees him travel Pole to Pole in search of deadly wildlife, starts on BBC1 at 5.30pm tonight