Ojos del Salado: the highest volcano on Earth — and one of the quietest

How high is “highest”? Where Ojos sits on the mountain

Two numbers do most of the work. Ojos del Salado's summit is usually given as 6,879 m(22,569 ft) — the figure in the Smithsonian's catalogue and our own — though careful GPS surveys have come in a little higher, around 6,893 m. Either way it clears every other volcano on Earth. The next-highest, nearby Llullaillaco, tops out at 6,739 m, a full 140 m lower.

It is not, though, the highest mountain in the Americas. That title belongs to Aconcagua at 6,961 m — about 80 m taller than Ojos, but not a volcano. So Ojos del Salado owns a precise record: the highest volcano, and the second-highest peak in the Americas. And it is a different crown from the one on our biggest volcanoes page — “highest point” is not the same as “biggest.” Hawaii's Mauna Kea rises only 4,207 m above sea level yet stands more than 10,000 m from its base on the ocean floor, which makes it the tallest mountain measured base-to-peak even though it is barely half Ojos's elevation.

Is it active? A two-eruption record

Here is the paradox that makes Ojos del Salado interesting rather than just tall. For a volcano this size, it does almost nothing. Our eruption record for it contains exactly two entries: a confirmed eruption around 750 CE and an uncertain report of minor gas-and-ash emission in 1993 that was never fully verified. The Smithsonian also flags a larger explosive eruption roughly 1,000–1,500 years ago that laid down pumiceous pyroclastic-flow deposits — but there are no confirmed eruptions in all of recorded history.

So why call it active at all? Because it still breathes. Ojos del Salado has persistent fumaroles — vents steaming sulfurous gas near the summit — and a Holocene eruption on record, which is enough to keep it off the extinct list. It is the textbook case of a volcano that is geologically alive but behaviourally quiet, the opposite of the busy peaks on our most active volcanoes ranking. Tellingly, the runner-up in height, Llullaillaco, actually erupted more recently than Ojos — in 1877 — making it the highest volcano with a confirmed historical eruption, even though it is 140 m shorter.

All of this is a product of where it sits: the Central Andean Volcanic Zone, where the Nazca plate grinds beneath South America along the Ring of Fire. That subduction built a dacite stratovolcano complex of overlapping cones, domes and craters — the machinery for violent eruptions — that has simply been idle for a very long time.

The world's highest lake, in the world's driest desert

Near 6,390 m on the eastern side of the summit sits a permanent crater lake about 100 m across — widely regarded as the highest lake of any size on Earth, higher than any in the Himalaya. What makes it strange is the setting: Ojos del Salado rises out of the Atacama Desert, among the driest land on the planet, where some weather stations have gone years without measurable rain. A pool of liquid water that survives year-round at that altitude, in that aridity, is a genuine curiosity — kept from freezing solid, in part, by the volcano's own geothermal warmth.

That dryness also explains why Ojos is a mountaineering objective rather than a lava-watching one. There is no glowing crater, no ash plume, no lava lake to photograph. People come for the altitude itself — the chance to stand on the highest volcano on Earth — and for the surreal, Mars-like landscape of coloured mineral slopes and high-desert light that the arid flanks create.

Climbing Ojos del Salado from Copiapó

Ojos del Salado, quick answers