For successful wadi-bashing, you need four-wheel drive and a good head of steam. Land Rovers and Cherokee jeeps are preferred. Pulling out the throttle, you race along the wadis, making a run at the dunes. Some dunes, enormous, dwarf a three-story house. Lying between them are the wadis, old water courses dry most of the year. In the rainy time they flood, and men and animals parched for water have drowned in the desert. The bashing isn't when you hit the wadis but when you top the dunes, a bone-jarring experience. I learned this in Dubai on the coast of Arabia.

A wink of prosperity under the desert sun, Dubai is squeezed between water, sand, and a high place. The water is the Persian Gulf or Arabian Gulf, depending on who makes the map. Below the Strait of Hormuz, thirty miles wide, a spiny headland, the Ru'us al-Jibal, cuts this body of water in two. The Emirates, all but one, huddle together on the Ru'us al-Jibal. Besides Dubai, they are Ajman, Sharjah, Umm al-Qaiwain, Ras al-Khaimah, and Fujairah. Abu Dhabi, the capital, lies along the mainland coast. Behind the coast are lumpy mountains, like tufts of carded wool, says the Sura, a verse from the Koran. The Tropic of Cancer bisects the lower reaches of this Trucial Coast. South and west of the imaginary line is the desert. Occupying a quarter of a million square miles, it peters out in salt plains this side of Mecca, not far from the Red Sea. Between the foothills of Oman and the Yemeni border, nine hundred miles away, the land is empty. Here is a dead land, said Doughty, an English traveler in the