Between the undulating rocky peaks of Valle de la Muerte lie massive sand dunes, the result of millions of years of wind erosion across the earth's oldest exposed surface.
English speaking tour guides from San Pedro de Atacama run sandboarding trips to these dunes. Along with the outdoor sport, the tour comes with a lesson on the area's geology, a scramble around canyons and caves, and pisco sour sundowners atop a ridge overlooking the red rock canyon-land of Valle de la Luna.
The driest place on earth
For most people entering the driest place on earth for the first time, the immediate question is how it came to be. Heading out of San Pedro at 4 p.m. on a hot summer day, our tour guide filled us in.
More than 30 million years ago, northern Chile was a wet environment, full of streams that carved up the sandstone landscape of the Pre-Andean Depression, or today's Atacama Desert.
Two major geological events changed all this. The opening of the Tasmania-Antarctic passage around 33 million years ago caused a new current - the proto-Humboldt Current - to flush cold water along northern Chile's shores, starving the area of coastal precipitation.
Some millions of years later, an uplift of the Andes caused what's known as a "rain-shadow," and moist air from the Amazon Basin was now blocked from the east. For much of the last 25 million years the Atacama has been in a state "hyperaridity," maintained today predominantly by the Humboldt Current.
Dune riding
Some way in to this dry, Mars-like landscape, we come upon the Grand Dune. When sandboarding in Valle de la Muerte, be prepared for a workout. The dune is almost 100m at its highest, and while you won't be covering that full distance, trekking up to the ridge multiple times breaks a sweat.
After a five minute lesson from our guide atop the ridge, we are instructed to go for it. Sandboarding is a close cousin to snowboarding, though it is a lot harder to transition from the toe to the heel edge and vice versa.
Once you get your confidence up, ask your guide to wax your rental board; this will get your speed up which makes turning easier, and increases the fun element tenfold. With speed, the whole experience is exhilarating, making the hike back up well worthwhile.
The Valley of the Moon
After about eight rides each we pack up the bus and head into Valle de la Luna. We disembark after a ten minute drive, and go on a scramble through some old limestone caves. Some are pitch black inside, but switch on a torch and the cave walls glint with quartz crystals that give off an eerie green glow.
Eventually, we summit a large ridge, and take in the wide expanse of both valleys around us. Evaporites - mainly halite or rock salt - have coated large swathes of the area in white crystals. Volcanic activity and relentless winds have further tortured the landscape, creating an environment that is likened to the surface of the moon.
We sip on pisco sours provided by our guide, and watch as the setting sun bathes the desert in a blood red and orange.
The sandboarding and sundowner tour costs CLP 12,000 from most operators in San Pedro. If necessary, make sure to ask for an English speaking guide.