Eduardo Avaroa

Declared in 1973, it protects a volcanic altiplano averaging over 4,500 metres in Bolivia's far south-west, celebrated for the Laguna Colorada, whose deep red comes from blooms of microscopic algae and mineral sediment, and which is critical habitat for three species of high Andean flamingo. Its geothermal fields — known as Sol de Mañana — with geysers, fumaroles and pools of boiling mud above 4,800 metres, are among the highest active geothermal systems on the planet. It is the usual final stage of the multi-day 4x4 circuits that cross the neighbouring Salar de Uyuni, the largest salt flat in the world.