Looking for wide open spaces? They don't come any wider than the Nullarbor plain

Its name means 'no trees', and the first European to cross this vast southern tract described it as 'a hideous anomaly'. Both wrong, says Kathy Marks, as she goes on a 1,750-mile road trip of a lifetime

At dawn the Nullarbor roadhouse was just a navy blur, but as we left and drove down the highway, the sun squeezed over the horizon, a perfect yellow disc. Shafts of light made the bitumen sparkle; a red-brown landscape stretched to infinity in every direction. Overhead arched an enormous dome-shaped sky.

At dawn the Nullarbor roadhouse was just a navy blur, but as we left and drove down the highway, the sun squeezed over the horizon, a perfect yellow disc. Shafts of light made the bitumen sparkle; a red-brown landscape stretched to infinity in every direction. Overhead arched an enormous dome-shaped sky.

It was day four of a marathon journey across the Nullarbor Plain, a 750 mile-wide chunk of limestone sandwiched between the Great Victoria Desert and the southern Australian coast. Not since the small settlement of Norseman 48 hours earlier had we seen a town; or been able to use our mobile phones.

The Nullarbor separates the population centres of south-eastern Australia from the west and, until recently, was regarded as a monotonous expanse, best traversed at speed. The first European to cross it, Edward John Eyre, called it "a hideous anomaly, a blot on the face of nature, the sort of place one gets into in bad dreams".

That description seems unduly harsh, and even the name (a squashed rendition of "no trees" in Latin) is undeserved, for there are plenty of trees on the plain - albeit mostly gnarled, stunted things, bent double by the wind. The Nullarbor has a peculiar beauty, particularly for frazzled urban dwellers, and the drive across it is now acknowledged as one of the world's great road trips.

The dramatic desert scenery, flat as a billiard table, is only part of the appeal. There are the quirky, incredibly isolated roadhouses that dot the Eyre Highway (named after the explorer), which are the only places to sleep and eat. There are towering limestone cliffs at the Head of Bight, where you can watch whales frolic. Further east, at Baird Bay, you can swim with sea lions and dolphins.

The expedition is generally considered more rewarding from west to east, and although the Nullarbor begins at Norseman, in Western Australia, most travellers set off from Perth, 454 miles further west. From here to Adelaide is 1,750 miles, for which you need at least a week.

On leaving Perth, you follow signs for Kalgoorlie. This is the least exotic stretch of the journey, through a wheat-growing region dotted with farms and weatherboard houses. Worth a brief stop is the Rabbit Proof Fence Reserve, just east of Merredin, which marks the start of the 1,145 mile-long fence erected to keep rabbits out of Western Australia's farming areas. Philip Noyce's 2002 film Rabbit Proof Fence was based on the story of three Aboriginal girls who ran away from an institution and found their way home by walking the length of the fence.

Stay overnight in Kalgoorlie, a colourful gold-mining town surrounded by imposing slag heaps, 375 miles east of Perth. "Kal" is notorious for its brothels and numerous pubs - 90 or so in its heyday. Gold was first discovered (by three Irishmen) in 1892, and the town still has a raw edge. There is more gold at Norseman, a drab town distinguished only by a curious sculpture of tin camels. From here, head east: you are now on the Nullarbor, the world's largest slab of limestone, covering more than 96,525 square miles.

The landscape is strikingly bare, with low scrub and the odd tree sticking up in splendid isolation, a spindly silhouette against a sharp blue sky. Traffic is scarce, and the red gravel verges are littered with dead animals. Large crows feast on the carcasses. The sense of empty space, of driving through a vast nothingness, is gripping. You feel dwarfed by nature.

The next speck of civilisation is Balladonia, a roadhouse with motel rooms, a caravan park and restaurant. Balladonia made world headlines in 1979 when it was showered with debris from the US Skylab space station, which disintegrated as it re-entered the Earth's atmosphere. The roadhouse - which has a little historical display - received an apologetic telephone call from President Carter and a visit from Miss America, who was in Perth for the Miss Universe finals.

Bordering the Eyre Highway are huge sheep stations farmed by the likes of Paul and Christine Ryan, who run 20,000 sheep on half a million acres at Fraser Range. The terrain is so dry that each sheep needs 25 acres, but the Ryans are smitten by their surroundings. Christine says: "It's the guts of Australia." Their "neighbour", James Ferguson, who lives 250 miles away, says: "It's nature in the raw. Every tree around here has been sown by nature, not man. Every animal has been bred without human intervention." The land looks barren, but it harbours 50 species of eucalypts, including slender copper-barked gimlets and vividly coloured, 82ft salmon gums. Amid the spinifex grass and saltbush roam emus, wombats, kangaroos, dingoes and even herds of wild camels - descendants of the beasts that played a crucial role in settlement of the Outback.

East of Balladonia is a 90-mile stretch of highway so hypnotically straight that you can almost take your hands off the wheel - or, in the case of the occasionally spotted masochistic cyclist, the handlebars. The arrow ends at Caiguna, where there is a famous blowhole; an extensive network of caves lies below the Nullarbor, with the best access at Cocklebiddy.

One drawback of travelling in Outback Australia is the cuisine. Don't expect to find anything nutritious or tasty. In some cases, don't expect to find anything at all. At one roadhouse, the Madura Pass Oasis Hotel Motel, we turned up famished, to be told by the uninterested owners that there was nothing for lunch. How about some chips? The chip pan wasn't working. A hamburger? No can do. We lunched on crisps that had passed their sell-by date.

On long sections of the journey, there is little to see. The tourist map promised a "Lobster Museum" at Mundrabilla, but when we arrived, mildly intrigued, we were told it was not yet open. What would it contain? Some crayfish. To compensate for the lack of "sights", you become fascinated by minute details: subtle variations in the browns of the landscape, the thickness of the dust coating your car, the loads carried by the triple-lorry "road trains" rattling past. Occasionally, and somewhat alarmingly, the highway is bisected by smooth expanses of concrete: landing strips for Royal Flying Doctor Service planes.

At Eucla, stop to gaze at the ruins of the old telegraph station, half buried by shifting sand dunes. Flocks of pink and grey galahs - small cockatoos - squawk in a nearby tree. When the overland telegraph was built in 1877, the lines from east and west met at Eucla. The bullock and camel trains left behind a dirt track, but it was not until 1941 - exactly a century after Eyre's intrepid crossing - that work began on a road; the sealing of the highway was not completed until 1976.

Cross the border and drive on to the township of Nullarbor, which consists of yet another roadhouse. A few miles away, the limestone plateau terminates abruptly in sheer cliffs, 260 feet high, as if it had been sliced with a knife. This is the Head of Bight, a spectacular spot and one of the best places in the world to view endangered Southern Right Whales. Between June and October, up to 150 whales congregate to mate and give birth in the warm, sheltered waters after migrating from sub-Antarctic feeding areas. More than 26,000 of the whales were slaughtered off Australia and New Zealand in the 19th century. Now the population is slowly recovering.

After leaving the Head of Bight, you re-enter civilisation, driving past the small beachside communities of Streaky Bay and Smoky Bay and through Ceduna, which seems like a veritable metropolis, with its supermarket and video store. At Baird Bay, well off the beaten track, Trish and Alan Payne have built two beautiful apartments overlooking the sweeping beach.

The Paynes are highly respected eco-tourism operators who take people out to swim with sea lions and dolphins in the wild. The interaction is completely on the animals' terms; the humans wait to be approached - and if their playmates are not in the mood, they are left alone. Trish has a special affinity with the dolphins, while the sight of Alan sends the sea lions - a rare species found only off parts of Australia - manic with excitement.

Swimming with the sea lions is a singular experience. As soon as you enter the water, these gentle, friendly creatures glide towards you. They nudge you playfully with their noses and copy your movements, rolling over and performing somersaults. They dive beneath you and gaze up at you adoringly with their liquid brown eyes, like Labradors. It is difficult to leave the water.

We spent our last night in Port Lincoln, a port town on the Eyre Peninsula, and then flew to Adelaide; that final leg of the journey has few charms. Had I not been so sick of driving, I would have happily turned the car around and driven back across the Nullarbor. That landscape haunts me yet.

GIVE ME THE FACTS

How to get there

Trailfinders (020-7938 3999; www.trailfinders.com) offers return flights on Qantas from London Heathrow to Perth, via Singapore from £549, for bookings made before 15 November. A week's car hire, pick up in Perth drop off in Adelaide, costs from A$370 (£147) with Thrifty (01494 751 600; www.thrifty.com).

Where to stay

The Quest, Yelverton, Kalgoorlie (00 61 8 9022 8181; www.theyelverton.com.au) has apartments sleeping two from A$165 (£67) a night without breakfast. A double room costs A$91 (£36) without breakfast at the Balladonia Roadhouse (00 61 8 9039 3453) and A$96 (£38) at the Nullarbor Roadhouse (00 61 8 8625 6271). Apartments for two at The Baird Bay (00 61 8 8626 5017) cost from A$85 (£34) a night without breakfast.

Where to find out more

Visit www.australia.com. Ask for a copy of the Australia Traveller's Guide (09068 633 235 (calls cost 60p/minute); www.australia.com). Western Australia Tourism ( www.westernaustralia.net), South Australia Tourism ( www.southaustralia.com), and ( www.nullarbornet.com.au).