Pinacate Biosphere Reserve

An hour's drive north of Puerto Peñasco, the Sierra El Pinacate rises from the Sonoran Desert in a landscape of black basalt lava flows, cinder cones, and enormous explosion craters. This is the Pinacate and Gran Desierto de Altar UNESCO Biosphere Reserve — a combined desert-volcanic landscape unlike anything else in North America. The giant circular craters (maares) are the most dramatic feature: massive depressions blasted out by steam explosions when rising magma hit groundwater, some of them nearly a kilometre across.

The reserve also contains the Gran Desierto de Altar, the only active erg (sand sea) in North America — massive dunes of up to 200 metres. Combined with the volcanic fields, it creates a landscape that feels genuinely alien. No specialist equipment is needed to visit the main craters, but a 4WD vehicle and plenty of water are essential.

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A story
The Pinacate is one of the youngest volcanic fields in North America — some of its craters are barely 10,000 years old, a geological blink. NASA used the craters to train Apollo astronauts before the moon landings: the bare black basalt, the lack of vegetation, and the extreme conditions were the closest approximation to the lunar surface available on Earth. The moonscapes the astronauts practiced on became, for a brief time, famous.