A Quiet Mountain That Exploded
On July 29, 1968, Arenal Volcano erupted without warning. The blast killed 87 people, buried three villages, and vaporized everything within several kilometers to the west. Before that morning, the local Maleku people had long called the mountain Arenal — a name tied to the sandy soils around its base — but almost no one outside the region had heard of it. Within a decade of the eruption, scientists from around the world were watching. Within three decades, it had become one of the most-visited destinations in Central America.
From 1968 until 2010, Arenal was one of the ten most continuously active volcanoes on Earth. Lava flows crept down its flanks almost every night. Guided night tours took visitors to lava-viewing platforms on the volcano's safe northeast flank, where the glow against the dark sky was something you could feel in your chest. Then, in 2010, Arenal went quiet. The eruption cycle ended, the lava cooled, and the volcano entered what geologists call a resting phase. The glow is gone for now — but the mountain is still there, still steaming on cool mornings, still dominating the horizon from every angle in La Fortuna.
The Town That Built Itself Around a Volcano
La Fortuna de San Carlos is the town at Arenal's base, and its entire economy pivoted around the volcano in a single generation. Before 1968, it was a small agricultural settlement — cattle, pineapple, yuca. After the eruption drew scientists, then adventurers, then package tourists, La Fortuna transformed with unusual speed. The main street now runs a dense corridor of outfitters, zip-line operators, hot-spring resorts, and sodas (the local term for casual Costa Rican restaurants) that would be unremarkable anywhere else but feel slightly improbable in a town this small, in a country with fewer people than the city of Los Angeles.
The transformation was fast enough that you can still see the seams. A working church faces a central park where local families gather in the evenings. School buses share the road with ATV convoys. The landscape beyond the tourist strip is still farmland — long views across cattle pasture toward the lake, cloud-draped mountains in every direction. What makes La Fortuna work is the ratio: the volcano draws the visitors, but the surrounding geography keeps delivering reasons to stay.
Rainforest That Actually Works
The forest around Arenal isn't decorative scenery. It's a functioning tropical rainforest — one of the best-preserved in Central America — and it rewards attention. The Arenal Volcano National Park protects roughly 12,000 hectares of primary and secondary forest on the volcano's flanks. Hanging bridges and well-marked trails give you entry points into a canopy that holds spider monkeys, three-toed sloths, toucans, coatis, and more species of birds than exist on the entire North American continent north of Mexico.
The humidity here is not incidental. Arenal sits near the continental divide, where Caribbean moisture pushes west and collides with Pacific air. The result is rain — sometimes briefly, sometimes for hours — at almost any time of year. Experienced visitors pack a light rain shell and consider the mist part of the atmosphere rather than an inconvenience. The forest is greener because of it. The waterfalls hit harder. La Fortuna Waterfall, a 70-meter cascade that requires a steep descent of roughly 500 steps to reach, is one of those places that photographs can't prepare you for. The sound alone is disorienting.
The Hot Springs: Why the Volcano Still Earns Its Reputation
Even dormant, Arenal heats the water flowing through its rock. The hot springs industry built around this geothermal resource is substantial — resorts range from budget-friendly public pools on the Rio Cholín to full-day luxury complexes with swim-up bars, waterslides, and price tags to match. The water is real. It emerges from the ground at temperatures between roughly 40°C and 50°C (104°F–122°F) and is channeled into pools at varying temperatures throughout the resort properties.
The springs change the experience of Arenal in a specific way: they give you something to do after dark and after a full day of physical activity. Zip-lining, hiking, white-water rafting, and horseback riding all compress well into one day. The springs extend it. Sitting in 40°C water while howler monkeys call in the tree canopy above you, with a version of the volcano silhouetted against the night sky, is one of those combinations that sounds like marketing copy but turns out to be exactly as good as advertised.
Lake Arenal and the Wind
The road west from La Fortuna follows Lake Arenal — a 33-kilometer body of water that's actually a reservoir, created in 1979 when a dam was built to supply hydroelectric power to much of Costa Rica. The lake is beautiful in the blunt, obvious way of large mountain water: blue on clear days, silver-gray when clouds move in, with the volcano reflected in the northeast end when the air is still enough to allow it.
The western end of the lake, around the town of Tilaran, is consistently one of the windiest spots in Central America. Kitesurfers and windsurfers have discovered this. For most visitors, the lake is simply the reason the drive west toward Monteverde is one of the more scenic stretches of road in Costa Rica — a long, winding route past cattle ranches, cloud forest, and water, with almost no traffic.
Wildlife: What You're Actually Looking For
Costa Rica contains approximately 5% of the world's biodiversity in less than 0.03% of the planet's land area. The numbers are real — the country made a deliberate decision starting in the 1970s and accelerating through the 1980s to protect its remaining forest, ban old-growth logging, and build an economy around nature tourism. The results are visible. Around Arenal, the wildlife concentration is high enough that a guided night walk near the forest edge will routinely produce tree frogs, katydids the size of a hand, sleeping birds, and the occasional kinkajou or porcupine without requiring any unusual luck.
The animals that attract the most attention are the easiest to find. Three-toed sloths move through the cecropia trees that grow along forest margins — they're slow enough that once a guide spots one, you can watch it for several minutes without it disappearing. Howler monkeys are audible before sunrise; their low, resonant calls carry for kilometers and are more frequently heard than seen. If you hire a naturalist guide for even one morning walk, you'll see things you'd walk past on your own without noticing: a basilisk lizard sleeping on a branch over the water, a morpho butterfly opening wings the color of a tropical sky.
The One Idea That Stays With You
What changes how you see Arenal — after the zip lines and the hot springs and the waterfall — is the timeline. The forest you're walking through is new. Before the 1970s, most of this land was cleared for cattle and agriculture, part of a broader deforestation wave that removed over half of Costa Rica's forest cover. The reforestation and protection policies that followed were not gentle or gradual: they required political will, economic sacrifice, and a bet that a small, poor country could build a sustainable economy on the promise of intact nature.
That bet paid off in a way that's now visible from the road. Where maps from the 1970s show pasture, you now see mature secondary forest — trees large enough to support canopy wildlife, streams clean enough for otters. Arenal Volcano National Park protects what's left of the primary growth. The surrounding area is a demonstration of what deliberate, sustained reforestation looks like over 40 years. When you look at the forest and think it looks ancient and untouched, you're seeing the success of a policy decision that was, within living memory, deeply contested. That's the thing worth carrying home.