It's a rare opportunity. There's no

It's a rare opportunity. There's no other way to stay the night on the salt flat except in this campervan. There are salt hotels on the lake's edge near the town of Uyuni, but nothing else that sits in the middle of this endless white expanse. We're isolated, but we're not exactly roughing it.

The previous morning, my friend and I were collected from Uyuni airport by Gustavo, our guide, in one of the town's ubiquitous Landcruiser four-wheel-drives. They are the hardiest vehicles for driving on the crusty salt pan, and Uyuni is littered with them.

We had flown from La Paz, a one-hour journey in a tiny aircraft that deposited us in this dusty, desert town. It's about 3500 metres above sea level, an arid place dotted with volcanoes on every horizon.

Gustavo takes us into the fairly unremarkable town centre for a coffee, before we begin our journey into the great white unknown.

There are more than 10,000 square kilometres of salt flat, and as our tyres crunch onto its surface, the size of the place and the challenge of navigating it become clear.