People in the UK kept telling me I was mad to bring my family to Zimbabwe, but look at this,” said Sir Ranulph Fiennes OBE, sitting on the banks of the Lower Zambezi river with his wife Louise, stepson Alexander and baby Elizabeth. The dry season was well advanced and hungry, thirsty animals had come into the Zambezi valley from hundreds of miles around. Lions roared downstream. Kudu and waterbuck drank from the river. Hippos were grunting and bellowing. Sixty yards away a huge bull elephant stood up on his hind legs to reach some high branches in a tree. “Marvellous,” he said. “In Antarctica, you go for months without seeing a single living thing.”

The concept of travelling for pleasure is a new one for Sir Ranulph, or Ran as he likes to be called. The lean, craggy polar explorer and professional adventurer probably knows more about endurance travel than anyone else alive. He once dragged a 217kg sledge across 1350 miles of Antarctica. In 1993, four months after double bypass surgery on his heart, he ran seven marathons in seven consecutive days on seven different continents. Even harder to fathom, for most people, is the fact that he sawed off three of his own fingers and most of a thumb in his garden shed on Exmoor, after getting them frostbitten in the Arctic. The fretsaw blade was “snagging unpleasantly” on his finger bones, so he went down to the village shop halfway through the operation and bought a finer blade. Although now aged 64, his exploits continue – he plans to climb Everest next year.

In 2005, for the 150th anniversary of Livingstone’s first journey down the Zambezi to Victoria Falls, Ran and Louise were invited to join a re-enactment of the journey in dugout canoes, camping on the Zambia side of the river. I went along as a journalist. For the first two days, Ran kept his head down and paddled with grim, remorseless determination, as if this was another endurance challenge. On the third day, the river started to crowd up with hippos, elephants and other game appeared on the shores, and a small miracle occurred. Ran Fiennes started to relax and enjoy his surroundings – something his wife had never seen before. By the end of the trip, he had decided to come back to Africa, take another trip into the bush, and do something for wildlife conservation.

He picked Zimbabwe because it has some of the best game viewing in Africa – the Big Five in three different national parks, no crowds or traffic jams, and the opportunity to go on walking safaris – and because its conservationists, guides, rangers and safari tourism operators need all the help they can get. His first stop was Victoria Falls, where our last trip had ended on the Zambia side. Here on the Zimbabwe side, the views were better and parties of Chinese and Korean tourists were breaking out into applause whenever a warthog or an impala appeared, as if the animals were part of a staged show. Then to Antelope Park in the Zimbabwe midlands, where he was the guest of honour at a captive lion-breeding and release project run by the African Lion & Environmental Research Trust (ALERT). From there, we drove north for six hours to Kariba, and caught a bush plane here to Mana Pools National Park.

“From reading the UK media, I was braced for aggressive police roadblocks, angry crowds, that sort of thing, but there’s been absolutely none of it,” he said. “Obviously the economy is a complete mess, and I’m not a Mugabe fan, but the people seem extremely nice, extremely patient and resilient, and very glad to see us. From what I’ve seen of Zimbabwe, it’s perfectly safe for tourists – as long as you don’t get out of your tent at night in a place like this.”

Lying in bed that night, listening to the wild cacophony, I made out a leopard coughing, baboons shrieking in alarm, lions roaring, elephants snapping big branches off trees and hyenas whooping. In the morning, I saw the footprints of a hippo that had walked right past my tent and stepped daintily over the guy ropes. After a quick pre-dawn cup of tea and bowl of cereal, we headed out on foot with James Varden, a professional guide with Natureways. Carrying a rifle and a pistol, he told us to move quietly and carefully. The baby and 11-year-old Alexander would have to stay in camp.

Almost immediately we saw a bull elephant. James motioned for us to sit down, whispering, “He’s relaxed right now and he’ll stay like that if we make ourselves small and non-threatening.” We watched the elephant slowly feed its way towards us, thirty yards away, then twenty. “Ummm, James,” hissed Ran. “Everyone stay calm,” James said. The elephant urinated then walked right past us, no more than ten feet away, with his gigantic penis dragging along the ground. “That always makes the girls’ eyes water,” quipped James.

We walked on, our senses springing to life. The main danger, said James, was startling a buffalo or a cow elephant with a calf, but there were also lions, leopards, perhaps a stray hippo or rhino to consider. James found fresh spoor from a pack of wild dogs, also known as painted hunting dogs, one of the rarest and most threatened species in Africa. We followed the tracks towards their den, passing zebra and impala, and then caught sight of one of the dogs, its huge ears erect, brown, white, black and reddish markings on its face. It barked and moved off, trying to lead us away from the den. Slowly we circled around and gradually the dogs relaxed and got used to us being there. After an hour, we were able to sit twenty-five yards away from the whole pack as they lolled around on the base of a termite mound.

“In most African national parks, you’re not allowed to do this, and you never really get the feel of being in the bush,” said James afterwards. “I’m afraid I might be ruined now for vehicle safaris,” said Ran.

Our next destination was Matusadona National Park. We crossed Lake Kariba by boat and arrived at the small, rustic game lodge of Rhino Safari Camp, just in time to see a young female leopard stalking an impala. It’s that sort of lodge – a few weeks ago a leopard ran right under the dinner table while people were eating, and lions, elephants, buffalo and hippos all wander through regularly, along with the rare black rhino.

The next day we tracked rhinos on foot with a guide and a wildlife biologist, and got within thirty yards of a mother and calf as they browsed through thick jesse bush. Poachers were still coming across from Zambia, said the biologist, and the rhinos’ outlook was bleak.

“What can we do?” asked Ran.

“Raise money, raise awareness and encourage tourists to visit,” the biologist replied – a message we heard over and again in Zimbabwe.

On his last night, Fiennes was the keynote speaker at a fundraising dinner at Meikles Hotel in Harare, with the proceeds going to various different Zimbabwean conservation projects. “There’s this idea in the UK that by coming to Zimbabwe, you’re supporting the regime and putting yourself in danger, and it’s simply not true,” he said afterwards. “By staying away from Zimbabwe, all you’re doing is making things even harder for all the people involved in tourism and conservation here, and depriving yourself of a fantastic time. I’ll be back next year, assuming nothing goes wrong on Everest.”