Rainbow Valley and Yerbas Buenas
Valle del Arcoíris is a valley of sedimentary hills banded green, red, white and ochre by the minerals in the rock, roughly 90 km north of San Pedro de Atacama. It is the excursion that gets dropped when a trip is three days long, and that is precisely what makes it worth taking on a fourth: it is the only place on this list where you can stand and look without anyone else in the frame.
What makes the colours
Mineral oxides in the sedimentary rock. Copper gives the greens, iron the reds and browns, salt and gypsum the white bands. Unlike everything else in this desert, the colours read strongest in flat midday light, which is why this runs as a daytime tour rather than a sunset one.
The petroglyphs at Yerbas Buenas
A short distance away, boulders carved with llamas, foxes, birds, and human figures by the people who drove caravans through this valley long before the Inca. They are unenclosed, unlit and unguarded. Skin oil is what destroys rock art, so look and do not touch.
Why it is empty
Ninety kilometres each way, and no sunset slot to build a tour around. It loses every time to Valle de la Luna, which is thirteen kilometres from town. The result is that a mid-morning visit here is quiet in a way that nothing else within reach of San Pedro is.
The fee
Collected on site, in Chilean pesos, cash only. Operators are explicit about it, and there is nowhere along the road to draw money.
Getting there, and how long it takes
Ninety kilometres north of San Pedro on Route 23 and then a gravel spur, which is about an hour and a half each way. Tours run six hours door to door and leave mid-morning rather than at dawn, because the colours want overhead light. It is one of the few excursions here that does not involve getting up in the dark, and on a week where three other days start before 5 a.m. that is worth something on its own.
What the altitude is doing here
Around 3,100 m, which is higher than San Pedro's 2,407 m but well below the 4,140 m of the altiplanic lagoons. It sits in the gap where you will notice the climb on a short walk and nothing more. That makes it a reasonable day two or three, and a sensible way to gain a little height before the tours that go properly high.
Why the petroglyphs are where they are
Yerbas Buenas sits on a route that carried llama caravans between the altiplano and the coast for well over a thousand years. The carvings are not decoration at a destination; they are marks left at a stopping place by people passing through, which is a different thing and reads differently once you know it. Many of the animals depicted are not local, which is the clue that the people making them were not either.
San Pedro de Atacama on Wikipedia
Frequently asked questions
Is Rainbow Valley worth the drive?
On a fourth day, yes. On a three-day trip the geysers, Valle de la Luna and the altiplanic lagoons come first.
What time of day is best for the colours?
Midday. The mineral bands read strongest in flat overhead light, which is the opposite of the rest of this desert.
Can you touch the petroglyphs?
No. They are unprotected and skin oil is what degrades rock art.
Sources