I discovered extreme fear.
But the 42-year-old presenter of CBBC wildlife show Deadly 60 - in which he swam with a great white and caught a king cobra - admits heis lucky to be alive after his latest adventure.
The naturalist has embarked on one of the most dramatic and dangerous expeditions filmed by a BBC crew, to explore Venezuela's tepuis - the ancient, sheer-sided, table-top mountains of Canaima National Park.
With a team of expert rock climbers, Steve attempts the first-ever ascent of a remote tepui to search for wildlife on the summit.
During the month-long expedition, he encountered creepy crawlies such as the Brazilian wandering spider, bullet ants and tarantula hawk wasps. He scaled untouched mountain cliffs and abseiled off the highest waterfall in the world - the Angel Falls in Rio Caroni, which has an uninterrupted drop of 2647ft.
Steve said: "The first ascent of the mountain was one of the most dangerous things I've ever done. We were very lucky to make it out alive.
"It took us all by surprise how malevolent and dangerous the climb turned out to be."
Steve is a children's TV favourite thanks to the scary things he's done and met for Deadly 60. But for him, this was a bucket-list dream that nearly turned into a nightmare.
He added: "I went to Venezuela looking for adventure.
"It turned out I got a whole lot more than I bargained for. Filming this series was simply unforgettable. I've been waiting a lifetime to see some of the wildlife I saw. It can be found nowhere else on the planet.
"But it was also one of the most challenging expeditions I've been on. It was a bit of a white-knuckle ride from start to finish."
The programme will follow Steve and his team as they climb for five days non-stop to conquer an unclimbed mountain.
Not bad for a man who broke his upper back in two places when he fell 30ft while rock climbing in 2008 in the Forest of Dean. He also shattered his left foot and it took six years to fix.
But there he was, hanging in a harness, hundreds of metres up an unclimbed summit with cockroaches crawling over his feet, rocks hurtling down at his head from above and the weather closing in.
Steve said: "Nervous doesn't describeit-terrifiedwouldbe more like it. But I learned enormous don't be climbed Steve amounts: That even the best climbers in the world can get scared and that some mountains just don't seem to want to be climbed. Then the rewarding knowledge that there are still dark corners of our planet left to be explored - and they are often utterly spectacular."
On one rock ledge where they slept, they found scorpions, bullet ants (the world's most painful stinging insect) crawling through their boots and sleeping bags. There was no let-up in the adventure.
Because they were living on a vertical rockface for nearly a week, they had to watch how much weight they were carrying so food was freeze-dried.
Steve reckons the two-part programme, which starts on BBC 2 tomorrow night, will be breathtaking for viewers.
He said: "They can expect to feel what it's like to be on an expedition like this. They'll feel the grime, the sweat, the fear and the pain. It's a gritty and real documentary about an epic adventure in one of the world's grandest locations."
" Over the years, Steve has swum in the Antarctic, was one of the first to climb Mount Upuigma in Venezuela and ledeven the the first western expedition into the crater of Mount Bosavi in Papua New Guinea.
in the scared and mountains want to climbed Backshall He reckons it's important to keep exploring places like Canaima National Park.
He said: "Knowing there are still places on our planet that are wild and wonderful inspires people to want to learn more and proves there are things worthy of protection.
"Conservation was never the primary aim of this expedition but it has filled me with passion to find out more about protecting this wondrous Shangri-La at the end of the Earth."? Steve Backshall's Extreme Mountain Challenge starts tomorrow on BBC2 at 8pm.
Over the years, swum in the was one climb Upuigma the crater Bosavi New He important exploring Canaima He scared I learned enormous amounts: even the best climbers in the world get scared and that some mountains don't want to be climbed Steve BackshallSteve Backshall on deadliest challenge yet - scaling remote Venezuelan peaks
AGONY ANT... Bullet ant sting is said to cause as much pain as gunshot wound
STRICTLY... Steve lifts Orla