Reaching the foot of plum-purple Volcan Licancabur, limbs aching and gasping for breath, I turn, expecting to see the jeep I left so long ago a speck on the horizon. Instead, about 50ft away, my fellow passengers are staring at me, a mixture of sympathy and amusement on their wind-cracked faces. A packet of crisps I brought with me from Chile is swollen and straining to burst. My head feels the same way. This is my first taste of life on the altiplano, and it's taken my breath away. Literally.
Surrounded by the tourist titans of Peru, Argentina and Brazil, Bolivia remains a sheltered secret. Famous for its drug wars and political unrest, the country also serves up a heady cocktail of stunning scenery, bustling cities and a surprising diversity of wildlife. Despite heavy land losses in a series of ill-advised wars, Bolivia still spreads over 650,000 square miles across central South America, and lays claim to some of the continent's finest natural attractions - the Amazon, the Pantanal and Lake Titicaca all lie within its borders.
But it's the Salar de Uyuni - the world's largest salt flats - that I've spent five hours driving through the Atacama Desert on a suspension-shy bus to see. Our starting point is San Pedro de Atacama, a dusty pueblo on the Chilean border with Bolivia. True independent travel is still an option here (we bumped into a Canadian backpacker at regular intervals as he negotiated with locals for a ride across the border), but for a better understanding of the area, a guide - and a four-wheel drive - are vital.