Welcome to Desierto de la Tatacoa
Tatacoa isn't really a desert, although the thermometer says otherwise – it sometimes hits 50°C. It's technically semi-arid dry tropical forest, averaging 1070mm of rain annually. Surrounded by mountains, the peaks around Nevado de Huila (5750m) grab most of the incoming precipitation, leaving 330-sq-km Tatacoa arid. The result is an ecosystem unlike anywhere else in Colombia – there are scorpions and weasels, fruit-bearing cacti, and at least 72 bird species.
To get to Tatacoa, you'll have to pass through Neiva, the capital of the Huíla department and a port on the Río Magdalena. From there take a colectivo one hour northwest to Villavieja. You can spend the night in Villavieja or in the desert.
Bring sturdy shoes (there are cactus spines on the ground) and a flashlight (torch).