That the word sounds like a cross between clown and buffoon is a happy coincidence, because it is not a pastime for the fashion-conscious. Genuine kloofers wear sun-hats, swimming trunks and soggy shoes, and carry rucksacks and lilos.
Kloofing becomes compelling because it is so utterly simple. All it involves is finding the quickest way down a river valley. Just look for the water and follow it.
Who needs those long treks in searing heat over ridge and peak? Kloofing is nature's way of negotiating a valley - and it's a lot of fun.
We left Cape Town in the middle of a hot summer afternoon, and drove north-east for a couple of hours, past Paarl and through the valleys of the Hawekwas mountains, deep green with vineyards on either side. The first rule of kloofing is to find yourself a river and and head towards its source. So, as the evening drifted behind the layers of hills, we set off to climb over the saddle in the peaks above us and into the valley behind. The moon was rising full ahead of us, bidding farewell to the heat of the day - perfect conditions for tackling the ascent.
We slept out near the top, and next morning started down what at this point was a wide, empty, craggy valley. Below us, we could see our way out: the deep gash in the landscape that is the kloof, or gorge, of the Wit Els (white alder) river.
At the edge of the gap, we changed out of our shorts and into our swimming trunks, took off our sandshoes and put on walking boots, and blew up our lilos.
This essential item among a kloofer's equipment is used to float the rucksack when the river becomes too deep to wade. Of course, the rucksack's contents should be well wrapped in waterproof bags: wet sleeping bags and unhappiness correlate strongly.
From the moment the route is decided by the whims of river and rock, the kloofer increasingly becomes part of the water. That does not mean just wading when the stepping stones give out, and swimming when the wading gives out, with the pack gently nursed along on its lilo; it means feeling that you are part of the flow downstream. The art is to go with the river.
There are moments when you find yourself leaping from boulder to boulder in a smooth rhythm, the path opening up ahead like a mist clearing to reveal a lost road, every footstep following the next in headlong momentum. Then you stop and look ahead, restless like an eddy, searching for the way down, stepping cautiously into the water, edging forward on slippery stones until a rock is in the right place. And you are off again.
When it becomes easy to meander, you float along the towering sides of the gorge, and all the sounds of the river merge into a natural kind of silence. This is the way the river runs, and so, it seems, do you.
The Wit Els is more than 20km long, so we did not dawdle: it took two-and-a-half days to come down, stopping at night on small beaches, sleeping beneath the patch of stars visible between the valley walls. The moon comes and goes quickly across the gap, then the dawn brings a new light to the rocky tops.
Like us every morning, the river seems sparkling and lively again. If the stepping stones give out, it is simpler to walk with the river a while than search for a path. And if the thorny bushes begin to crowd the banks, it is much more pleasant to remain knee-deep in the clear, smooth-flowing water. The river becomes compelling, with its delicious dark pools and bubbling white rapids, its huge diving boulders and smooth water-sliding rocks.
Our oddly attired procession ended where the Wit Els flowed into another river - one with a road beside it, and cars and people. I stepped off the last boulder, on to the bank. But even after I had reached the road, my feet still seemed to be dancing on the rocks, eyes concentrating on the next leap, the water racing past, a pool looming deep and tempting.
At present, the lilo sits in the corner of the hallway drawing mocking comments from passersby - but I know its day will come again.
Getting there: a London-Cape Town flight on South African Airways through Quest Worldwide (081-547 3322) costs pounds 458 if you travel before 13 October. Beyond that date, Bridge the World (071-911 0900) has a fare of pounds 560 on SAA or British Airways for outward travel before 9 December.
Recommended reading: South Africa, Lesotho and Swaziland - a Travel Survival Kit (Lonely Planet, pounds 10.95).
Further information: the South African Tourism Board is at 5/6 Alt Grove, Wimbledon, London SW19 4DZ (recorded information on 0891 102090, a premium-rate number).