Margaret Bradley treks through Namibia's Fish Canyon
Over two-and-a-half days, 74mm of rain fell in the Fish River Canyon - a whole year's rainfall. The gravel road was covered with treacherous drifts of sand deposited by ephemeral rivers; part of the lane leading to the canyon itself was washed away and the airstrip was filled with fissures created by swift flowing floods.

Worried and apologetic because of the state of the rough lane, the manager of the Canyon Nature Park rang to warn us that the camp could only be reached in a 4x4. But we were delighted by the unseasonal storm for, though the Fish River itself was no longer running when we arrived, water was still cascading down the creeks and seeping through the Canyon floor to replenish the permanent pools.

We drove down to base camp across mile after mile of high desert and scrub savannah. At regular intervals, interspersed with the huge nests of sociable weaver birds, we passed pale chanting goshawks on the telegraph poles, watching for prey. At ground level - amongst sand and quartzite boulders - grew fat succulents, southern Africa's answer to the cactus.

Some 110 miles from the town of Keetmanshoop, invisible until you are almost on top of it, the Fish River Canyon is a huge tear in the face of the earth. In the mists of geological time, a sea bed was lifted miles above the level of the ocean and weathered into ranges of table mountains. Then some 500 million years ago, a fault opened up among them. Widened by glaciation and altered by more faults and wind erosion, canyons within canyons were formed until 50 million years ago a river began to flow down them. Now 100 miles long and up to 16 miles wide, this natural wonder is second only to the Grand Canyon as a gouge in the globe.

Every year the Ministry of Environment and Tourism allows a limited number of hikers to spend five days walking 53 miles of the canyon's meanders - from the Main View Point opposite Hell's Corner to the hot springs at Ai Ais. First they must produce a recent doctor's certificate, as the only way to bring in medical aid is by helicopter from Windhoek, the capital, 700km away. And they must carry with them all their equipment, from tents to food and cooking utensils.

Wanting more comfort, we opted for a newly opened alternative, the camp at the Canyon Nature Reserve, which has been set up by Lex Van Den Bosch, a Dutch biologist and tour guide, and his partner Loes Bolle. Seven guest tents have been permanently pitched on stone bases along the very edge of the canyon with a view across miles and miles of fissures, gorges, hanging valleys and plateaux to a range of table mountains beyond. Everything is clean and simple, from the latrines to the solar heated bucket showers - simple, that is, for the guests: Lex and Loes have had to buy every item of building material, furniture and food from Keetmanshoop, some six hours' round trip away, or from Windhoek.

The evening of our arrival, just after the sun had set leaving a streak of yellow and duck egg blue in the west, the full moon rose from the direction of South Africa's gold fields. It had a striking effect, for the fields looked as if they were resting on the brink of the world and dimming the stars all night.

The next day, we set off along the lip of the canyon, following tracks of Hartmann's mountain zebra and curly horned kudu. We saw the tiny, twin hoof prints, no bigger than a pair of 5p coins, of the klipspringer and skirted its latrines - a klipspringer and his mate may use the same place to defecate over many years. Sometimes we startled kestrels, which rose from their look-out rocks and wheeled with motionless wings ever higher and higher on the desert thermals.

By late afternoon we had reached a large, permanent pool in the river bed, flanked by a wide sandy beach, and a thicket of acacia trees. As the overhanging precipices were beginning to glow dusky pink in the sunset, Lex and Loes unlocked a stone box and took out cooking equipment, sleeping bags and tents, which we each set up on the sand in the position we thought would give us the best morning view.

We were not disappointed. At sunrise the cliffs turned to gold and, gloriously out of place in this usually parched wilderness, a cormorant dived for catfish in the pool.

We began our return journey over a plateau of black limestone eroded into strange dimples that looked like egg trays for a dolls' house. Then we crossed a plain of red-brown quartzite where, in the sandy gaps - startled into life by the unseasonable rains - the pointed, curled leaves of a bulb were sprouting.

Towards the head of the valley, we came across strange, stunted plants adapting to desert life, and camel thorn trees, which seemed to reach out for our clothes with their long, grey, skeletal spikes. "Take nothing but pleasure and leave nothing but footprints in the desert," the Namibians say. Apart from a few torn clothes, we did just that - and loved every minute of it.

The only flights betweenLondon and Windhoek are operated by Air Namibia (0181-944 6181).

The current lowest fareis pounds 651 (including taxes)

for a minimum stay of 10 days, maximum four

months. For more information contact the

Namibian Tourist Office, 6 Chandos Street, LondonW1M OLQ (0171-636 2924).