Don't look down

Mark MacKenzie tests his head for heights while rock climbing across the 'roof of Africa' - on a horse

Hidden among the saw-toothed peaks of Lesotho's Maluti mountains is a high pass known as "the neck". Here, the rough road that originates in Maseru, the nation's capital 50 miles to the south, narrows to pass between two rocky outcrops. On one, a plaque reads: "Wayfarer, pause and look on a gateway of paradise". This is the entrance to the Thaba Putsoa, a dramatic range notable for two things. The first is that, in summer, the mountains nurture vast meadows of mountain flowers. The second is that the Putsoa is home to the country's Basotho horsemen, arguably the only indigenous horse culture in sub-Saharan Africa.

Hidden among the saw-toothed peaks of Lesotho's Maluti mountains is a high pass known as "the neck". Here, the rough road that originates in Maseru, the nation's capital 50 miles to the south, narrows to pass between two rocky outcrops. On one, a plaque reads: "Wayfarer, pause and look on a gateway of paradise". This is the entrance to the Thaba Putsoa, a dramatic range notable for two things. The first is that, in summer, the mountains nurture vast meadows of mountain flowers. The second is that the Putsoa is home to the country's Basotho horsemen, arguably the only indigenous horse culture in sub-Saharan Africa.

The dedication was written by one Mervyn Bosworth-Smith, a Harrow schoolmaster who, in the 1890s, was so captivated by the Putsoa's imposing peaks that he decided to set up shop. The trading post he established in the settlement of Malealea served as a supply station in a land whose rugged topography earned it a grand old nickname: "The roof of Africa".

Today, Smith's store is run by Mick Jones, one of only a handful of native "white Basotho". The store is not what it was in its colonial-era pomp, but Jones has added a tourist lodge, which serves as a base for specialised mountain horse treks. For the next three days, I plan to take part in what must qualify as one of the more bizarre adventure experiences available: rock climbing on horseback.

Over coffee, Jones runs through a history of his homeland. A landlocked enclave within South Africa, Lesotho's tribal society is predominantly agrarian and its major natural resource, apart from the steady supply of labour it sends to South Africa's mines, is water. Such is the importance of rain to the nation's subsistence farmers, the Basotho call it "white gold". But it is the Basotho's horse culture that sets them apart. Lesotho is the only country in sub-Saharan Africa where horses were bred for indigenous, rather than colonial, needs; and this makes the location all the more incongruous - the mountain kingdom of Lesotho is the only country in the world whose entire territory is located above 1,000m.

So while the native Basotho pony may be renowned for surefootedness and endurance, logic suggests you'd be better off with a monkey.

The next morning myself and my riding partner, Amanda, meet Clemence, our guide, who introduces us to our mounts: Black Power for Amanda and Sister for myself. By European standards, Basotho equine management is idiosyncratic to say the least. Heading out on our first morning, Clemence encourages our pack horse to keep pace through regular tugs on a rope attached to its lower lip. And the traditional method of dealing with a horse's aches and pains is to give it dagga (marijuana).

The first day's ride out of Malealea takes us across the Phitseng plateau, through flower meadows which every so often disappear into dongas; steep, eroded trenches which lie in wait for the unwary. After lunch we reach the vertiginous Makhaleng Gorge and, as I scan the horizon for anything vaguely resembling a bridge, Clemence begins to laugh. "The Roof of Africa," he says enigmatically, before pointing to a muddy ford on the valley floor, some 200 metres below: "That's where we're going."

In the absence of speed, the Basotho pony's talent as mountaineer of the equine world is little short of extraordinary. The downside is that to experience it, you need to be sitting on the back of one. Dropping on to the slick limestone that lines the gorge walls seems an unnecessarily hazardous way of testing your steed's capabilities. As the gradient steepens, the width of the path becomes narrower and narrower. At one point, the view to my left consists of my left knee, left boot - and fresh mountain air. Trusting my life to a (potentially stoned) horse requires a serious act of faith, particularly during the interminable pauses as my mount stops to check the next (possibly fatal) step.

Occasionally, rock fragments spray into the ravine below. "Close your eyes and ignore the rocks rolling down the mountain," Jones advised before departure. Given the basic principles of traction, this really shouldn't work. Slippery hooves should find little purchase on the sheer, slippery limestone. Yet such are the climbing skills of the Basotho pony that on one occasion, Mervyn-Smith is rumoured to have embarked on an overnight trip with an alarm clock around his neck. Set to go off at half-hour intervals, he woke only to check the pony was still on course. Our second day is spent climbing up one river bed after another, over terrain that would send European horses lame in an instant.

On our final night in the village of Sekoteng, we are granted an audience with the local chief, Puli. Life on the roof of Africa is changing, he explains. Hydroelectricity is big business in these highlands and flooding vast tracts of tribal farmland is considered a small price to pay in the relentless march of progress. For the Basotho pony, making molehills out of mountains is one thing, but walking on water is something else.

Horse trekking from Malealea Lodge starts from £22 per person per day, inclusive of guides and accommodation, tel: 00 27 51 436 6766, www.malealea.co.ls

Hit the adventure trail

Black water rafting in New Zealand

Invented about 20 years ago in the extreme-sports mecca of New Zealand, this involves underground rafting in flooded cave systems with only head torches to guide you ( www.blackwaterrafting.co.nz)

Biking on the Wild Coast

A unique mountain-biking adventure taking in some of South Africa's remotest coastline. Seven hours cycling a day will be spent either dodging wild rhino or swimming (bike and all) across river-mouths which are breeding grounds for large colonies of bull sharks ( www.180.co.za)

Hike the Appalachian Trail

Spanning 2,050 hundred miles, from Katadhin in Maine, to Springer Mountain in Georgia, the "AT" is arguably the greatest and oldest hiking route in the world with terrain to suit all fitness levels ( www.appalachiantrail.org)