Ice Cream Over a Lake of Acid

The best ice cream of my year was sold to me on the rim of an active volcano, above a lake of acid.

A quick pop-in

This was a quick but worthwhile pop-in to San Salvador, El Salvador: three days, and a delightful mix of adventure and relaxation. The adventure came first. The relaxation was medically necessary afterward.

Up Santa Ana

The highlight was scaling Santa Ana, the volcano Salvadorans also call Ilamatepec. At 2,381 meters it is the highest volcano in the country, and it is very much not retired: its most recent eruption was in October 2005.

The trek was 5 miles, up through green scrub and agave and out onto bare gray rock, in the kind of heat that makes you renegotiate every switchback. My legs are still recovering. My legs would like that on the record.

Then the crater opens up below you, layer on layer of rock wall stepping down to a lake in a shade of turquoise that looks like someone turned up the saturation. Steam drifts off the surface and the colors swirl. It is the kind of view that makes you forget about your calves for almost a full minute.

And right there, amid the swirling hues, commerce. Vendors were selling sorbetes, strawberry and turmeric, and in that sweltering heat it was a perfect treat. In El Salvador, sorbete is the word for ice cream, and artisanal sorbete is a proper national tradition, sold for generations from wooden pushcarts on street corners. I had mine on top of a volcano. I recommend this.

Why the lake looks like that

That turquoise is not a filter, and it is not fixed. The lake is closer to a status light.

Under Santa Ana sits magma, and magma breathes out gas, mostly water vapor plus sulfur dioxide and hydrogen chloride. That gas rises through the hot, wet rock under the crater, condenses into the groundwater, and turns it into acid. The result, in the crater, is a small lake (researchers measured it at roughly 200 meters across before the 2005 eruption) of sulfate and chloride brine, with a pH that has been recorded anywhere from about 2.5 down to below zero. For reference, lemon juice sits around 2. You do not swim in this lake. You look at it from up top, ideally with ice cream.

The lake also works as a scrubber. Gas bubbling up from below passes through the water, and the lake soaks up a share of the sulfur before it reaches the air. A 2019 study found that when the lake shrank, it absorbed less, and the gas escaping from the crater changed with it.

And the color moves with the chemistry. After the October 2005 eruption, volcanologists watching from the rim recorded the lake going from aqua green to lemon yellow, back to dark green as it refilled in 2006, aqua again in early 2007, then gray that March as it evaporated down to 4 percent of its former volume. In April 2007, small explosions went off from the lake, one of them about 40 meters high. The researchers tie the color changes to shifts in temperature, acidity and the minerals that dissolve or settle out as heat and gas from below come and go.

So the swirling hues are real information. The lake is, more or less, the volcano's mood ring. On my day, the mood was turquoise and steaming, which I am choosing to read as "welcoming, but do not touch."

The lighthouse next door

From the trail, the view next door is Izalco, a near-perfect gray cone that looks drawn with a ruler. It is also very young. Izalco was born in 1770 on Santa Ana's southern flank and then erupted almost continuously for close to two centuries, building a cone about 650 meters tall. At night its glow was visible from the sea, and sailors called it the Lighthouse of the Pacific. It went quiet after 1958, apart from a small flank eruption in 1966.

The Sheraton Presidente, and its residents

Back in the city, I was nestled in comfort at the Sheraton Presidente. The hotel has vintage charm, and it comes with amusing snapshots of the manager rubbing shoulders with global dignitaries, which is the most entertaining hallway decor I have seen in some time.

The real stars, though, were the residents: peacocks, roaming the grounds and adding a touch of whimsy to the whole operation. They were my favorites. I do not believe they noticed.

If you go

• The volcano. Santa Ana is climbed from Parque Nacional Los Volcanes (the Cerro Verde area), run by El Salvador's environment ministry (MARN). Hikes go out with authorized guides in the morning, and groups have generally left by around 11 a.m., so arrive early.
• The fee. Entry for foreigners is a few US dollars, but the published figure has changed more than once (reports range from $3 to $6). Check MARN's current rate before you go.
• The distance. Published distances for the hike run from about 7 km to 12 km round trip depending on the route and starting point. Mine was 5 miles. Plan for half a day.
• The crater. The gas can sting your eyes and nose, and in high winds MARN has limited time at the rim to as little as 10 minutes. Respect it.
• The heat. Sun protection, a hat, real shoes and plenty of water. Then the sorbete.
• The hotel. The Sheraton Presidente is in San Benito, a few minutes' walk from the Museo de Arte de El Salvador (MARTE). Keep an eye out for peacocks.

Until next time

Now, sporting a fresh tan and a coveted Starbucks mug, I am headed back to the comforts of home (boys, I am coming!). With memories in tow and legs still recovering, the call of future adventures is already ringing.

Three days is not long enough to know a country. It is long enough to climb its tallest volcano, eat ice cream over a lake of acid, and decide the peacocks are the best part of the hotel. Until next time, El Salvador.