Turrialba Volcano is the rugged, wilder twin of the nearby Irazú. Standing at 3,340 meters (10,958 feet), it is the second-highest volcano in Costa Rica and one of the most structurally complex. For nearly 150 years, Turrialba was a sleeping giant, overgrown with vegetation and visited by hikers who walked right into its green craters. That changed dramatically in the 21st century.

Today, Turrialba is one of the most active volcanoes in Central America. Its reawakening is a powerful reminder of the earth’s unpredictability, turning lush cloud forests into “ghost forests” of dead, gray trunks and periodically dusting the capital city of San José with volcanic ash.

The Twin Titan

Turrialba shares a massive base with Irazú Volcano.

The Connection: The two giants are often called “twins” because they are located on the same tectonic weakness. However, their personalities are different. While Irazú is famous for its lake, Turrialba is famous for its fumaroles (gas vents) and complex crater structure.
The Profile: Turrialba is less accessible and more rugged. Its slopes are cut by deep, sheer-walled canyons covered in dense montane rainforest.
Remote Beauty: Because it has been closed to the public for long periods due to activity, it retains an air of mystery and wilderness that the more commercialized Irazú lacks. It stands as a sentinel over the Caribbean slope, often shrouded in mist, its plume visible for miles.

The Sleeping Giant Wakes (2010-Present)

For over a century (since 1866), Turrialba was dormant. Farmers grazed cattle inside the central crater, and the area was known for its peaceful, alpine atmosphere.

The Awakening: In January 2010, the mountain signaled a change. Phreatic explosions opened new vents, ending the long slumber.
The Escalation (2014-2016): The activity intensified significantly. Massive eruptions sent ash columns 4,000 meters into the air. This ash travelled west, causing repeated closures of the Juan Santamaría International Airport in San José, affecting tourism and commerce mainly. The eruption of 2016 was particularly violent, ejecting incandescent rocks and reshaping the crater floor.
Recent Activity: The volcano remains in a state of high unrest, with activity continuing well into the 2020s. It frequently emits ash, steam, and magmatic gases. Access to the summit is strictly controlled and often suspended based on daily gas readings. The volcano is constantly monitored by OVSICORI (Volcanological and Seismological Observatory of Costa Rica), which uses a network of seismometers and gas sensors to track its “pulse.”

The Three Craters

Turrialba’s summit is a depression containing three distinct craters, aligned in a northeast-to-southwest direction:

Crater Central: The most active vent. This is where the recent explosive activity is concentrated. It has deepened and widened significantly in the last decade due to blasts and collapse. The bottom is often obscured by vigorous degassing.
Crater East: An older, grassy depression that used to be a visitor favorite before the restrictions. It represents an older phase of activity.
Crater West: Another dormant vent. The landscape shifts from lush greenery to a stark, gray moonscape as you approach the active rim, a testament to the localized destruction caused by the acid gas.

The Buried Forest: An Ecological Tragedy

The most striking visual feature of modern Turrialba is the “Buried Forest” or “Ghost Forest” (El Bosque Quemado).

Acid Burn: The constant emission of sulfur dioxide ($SO_2$) and acid rain has killed hectares of the surrounding cloud forest. The vegetation here was not burned by fire, but suffocated and poisoned by gas.
The Landscape: What remains are the bleached, skeleton-like trunks of massive oak and myrtle trees standing in fields of gray ash. It is a hauntingly beautiful scene that photographers flock to capture. It serves as a visual lesson in how volcanoes terraform their environment. The contrast between the dead, white trees and the swirling gray mist is surreal.
Regeneration: Interestingly, certain pioneer species of ferns and mosses have already begun to colonize the dead wood, showing nature’s resilience. The area has become a laboratory for biologists studying how ecosystems recover from volcanic sterilization.

Flora and Fauna

Despite the harsh environment near the summit, the slopes of Turrialba National Park are rich in biodiversity.

Birdlife: The park is a haven for birdwatchers. Species such as the Resplendent Quetzal, the fiery-throated hummingbird, and the sooty robin can be spotted in the lower, greener sections.
Mammals: The dense forests are home to coyotes, armadillos, porcupines, and the elusive coati. While they avoid the active crater, their tracks can often be seen in the ash of the lower trails.
Vegetation Zones: As you ascend, the vegetation changes from tropical wet forest to premontane rainforest, and finally to the stunted, high-altitude páramo vegetation near the summit (before giving way to the dead zone). Giant “Poor Man’s Umbrellas” (Gunnera insignis) with their massive leaves are a common sight along the roads.

Agriculture in the Ash Zone

The slopes of Turrialba are famous for the Turrialba Cheese (Queso Turrialba).

The Dairy Industry: The cool climate and fertile volcanic soil support rich pastures for dairy cattle. The region produces a distinct, salty white cheese that is a staple of the Costa Rican diet. It is protected by a Denomination of Origin.
Impact of Eruptions: The recent eruptions have been hard on farmers. Volcanic ash can coat the grass, causing digestive issues for cows (“fluorosis”) and abrasion to their teeth. Many farmers have had to evacuate their herds to lower ground during peak activity, adapting their traditional lifestyle to the volcano’s new rhythm. Crops like potatoes, cabbage, and carrots are also grown here, benefiting from the mineral-rich soil but suffering during heavy ashfall.

Tourism: The Adventure Route

Visiting Turrialba is an adventure compared to the drive-up ease of Irazú. After being closed for nearly eight years, the park reopened with new safety protocols.

The Road: The road to the summit was damaged by landslides and neglect but has recently been repaired. The drive offers stunning views of the Caribbean plains and the Reventazón River valley.
Guided Tours: Since the park reopened (intermittently) in 2020, visitors must usually be accompanied by certified guides. Hard hats are mandatory for all visitors near the crater.
The Hike: The experience typically involves a hike of about 4-5 kilometers (round trip). You walk through the “Ghost Forest,” past the historic “Central Lodge” (now abandoned and covered in ash), to a viewing platform overlooking the active crater.
The Senses: The smell of sulfur is potent, and the sound of the volcano “breathing” (jetting gas) poses a visceral reminder of its power. On a clear day, you can see all the way to the Caribbean Sea.

Guayabo National Monument

On the lower southern slopes of the volcano lies Guayabo, the most important archaeological site in Costa Rica.

The Ancient City: Between 1000 BC and 1400 AD, this was a thriving city of 10,000 people. They built aqueducts that still function today, paved roads (calzadas) that align with the volcano, and complex stone mounds.
The Mystery: The city was abandoned mysteriously around 1400 AD, before the Spanish arrived. Some archaeologists speculate that increased activity from Turrialba or a change in the hydrological patterns caused by the volcano forced the population to leave. The site suggests a deep spiritual connection between the ancient inhabitants and the smoking mountain above them.

Technical Facts

Feature	Data
Elevation	3,340 m (10,958 ft)
Volcano Type	Stratovolcano Complex
Location	10.02°N 83.77°W
Status	Active (Degassing & Ash Emissions)
Last Major Cycle	2010 - Present
Key Feature	The “Ghost Forest” & Fumaroles
Monitoring	OVSICORI-UNA

Conclusion

Turrialba is a volcano in transformation. It has gone from a pastoral, green mountain to a jagged, smoking ruin and is now slowly finding a new equilibrium. It represents the raw, landscaping power of geology. For the visitor, standing amidst the dead white trees looking into the churning gray abyss is a profound encounter with the forces that shape Central America. It is a place where beauty and destruction exist side by side, offering a stark contrast to the verdant paradise usually associated with Costa Rica.