Puddles of lime green water lie amidst an orange and rust colored crust riddled with strange mounds of pale blue salt. It's a palette of different hues that might almost suggest paradise, and yet the sun beats down relentlessly on the blistered earth, while the pooled liquid's beauty belies its extreme acidity. In a flash, notions of serenity evaporate in the face of nature's conditions at their harshest and most unforgiving.
The Danakil Depression in Ethiopia is a truly challenging place to visit. The terrain is difficult, much of it looking as if it belongs to some distant, inhospitable planet. The temperature is oppressive too: an average of 34°C (94°F) year round makes this the hottest place on Earth. And the heat doesn't only come from above.
Danakil is a bubbling cauldron of volcanic magma and springs rich in mineral salts. Yet it's not only the searing heat that makes this place unique: it also boasts one of the most bizarrely beautiful active volcanoes in the region, Dallol. At 120 meters (395 feet) below sea level, Dallol is the lowest-lying land volcano in the world.
The area has also spent significant periods of its past submerged under water. This last happened some 30,000 years ago when volcanic activity to the north created a natural wall, keeping out the Red Sea, which up until then had been periodically flooding the depression.
The hydrothermal field (as it is technically known) of Dallol is a pretty salty place. In places the salt deposits reach a depth of over a kilometer!
Some of the salt is the residue of the ancient seas that once flooded the depression, only to evaporate, leaving behind mineral deposits of sodium, calcium, magnesium, potassium, and a substance which was once heavily mined here: potash. In fact, this is one of the rare places on Earth where potash can be harvested above ground.
Newer deposits of salt and potash come from heated groundwater pushed up to the surface where it dries, often in beautiful and surreal patterns.
Initially, the deposits here are white, a color pretty much everyone associates with salt! Over time, the minerals react with oxygen to produce the brilliant colors for which Dallol is famous: yellows, reds and greens. Gas-emitting fumaroles push the salt up in some places, and over time form strange-looking hollow mounds and brittle, egg-shaped bubbles.
The true source of Dallol’s unusual landscape is thought to lie deep below all this salt: an active volcano buried far beneath the surface. It is believed that the molten magma from this volcano is what heats the groundwater, causing it to bubble up as hot springs.
The water in these springs is not only hot but also highly acidic, as their fluorescent green color suggests. Definitely not the kind of hot springs you'd want to ease into for a relaxing soak — or even step in accidentally.
Standing about 50 to 60 meters (165-197 feet) above this landscape is Dallol Mountain, believed to have been thrust up by the underground volcano. One side of the mountain has been eroded into spectacular canyons and pillars, some of them up to 40 meters (131 feet) tall.
Because of their mineral composition, these salty canyons are pinkish in color and striped with layers of stratified salt deposits. They are prevented from eroding away completely by the presence of gypsum anhydrite caps and beds of clay.
Surrounding Dallol is an area covered in rock salt and sediment, the latter a result of dried floodwaters. This mud and salt (or halite) mix goes down for a depth of a few meters, covering underlying deposits of potash.
Not far from the bubbling acid ponds of Dallol is another active volcano, this one above ground. Erta Ale (seen here at night) has been drawing visitors for decades with its spectacular burning lava lake. Tragically, in January 2012 a group of scientists and tourists were attacked by terrorists, leaving a number of them dead.
A shield volcano, meaning it has a wide base and gentle slopes, Erta Ale is rare because of its almost ever-present lava lake. Sometimes, the caldera at the top of the volcano will even hold two lava lakes at the same time! It's a sight few can resist, despite the dangers.
Fissures spew out basaltic lava that flows and pools around the volcano, forming swirling patterns of grey and black as it cools. The heat around the volcano is overpowering, as are the sulfur dioxide fumes.
This is no easy tourist destination. There are no roads, and trains to the area were discontinued years ago. Travel is by jeep or camel only — and even then under armed guard.
This is a volatile region, and not only geologically. Many Western travel advisories, including Britain and the US, warn tourists to stay away from the Danakil area because of ongoing conflict in the border region with Eritrea.
Still, many do brave the dangers of heat, political turmoil and noxious volcanic gasses, believing the experience of visiting a place of such geological and visual wonder is worth it. And for those who do, the Danakil Depression does not disappoint.