The supervolcano that left a 340-metre deep scar in Guatemala

Countries & Cities · Published 14 October 2026 Swipe more like this →

In short: Deep within the Sierra Madre mountains lies an enormous caldera, formed by a cataclysmic eruption 79,500 years ago. Today, Lake Atitlán is celebrated for its beauty, but its origins are written in ash and volcanic fury, hiding a history of both ecological tragedy and profound cultural resilience.

The basin of Lake Atitlán is the remnant of the Los Chocoyos eruption, a supervolcanic event that ejected up to 300 km³ of tephra. This explosion was so massive that its ash, known as Y-8, has been detected as far away as Florida and Ecuador, serving as a permanent stratigraphic marker in both the Atlantic and Pacific oceans. The lake itself is an endorheic body, meaning it has no outlet to the ocean, and is shaped by deep escarpments and three volcanoes on its southern flank.

While the landscape is breathtaking, its geological and biological history is marked by volatility. The three volcanoes—Atitlán, San Pedro, and Tolimán—represent different eras of activity. San Pedro is the oldest, having ceased erupting approximately 40,000 years ago, while Atitlán remains active, with its most recent eruption recorded in 1853. The region has also faced modern seismic shifts; a 7.5 magnitude earthquake in 1976 fractured the lake bed, causing water levels to drop by two metres in just one month.

Humanity and ecology have also faced sudden, often man-made, shifts. In 1958, the introduction of non-native black bass for tourism purposes led to the extinction of the Atitlan grebe and the loss of over two-thirds of the lake's native fish species. Simultaneously, the surrounding Maya communities, including the Tz'utujil and Kaqchikel, have navigated centuries of upheaval, from the Spanish conquest to the brutal 'scorched earth' policies of the Guatemalan Civil War (1960–1996). Today, the lake faces new threats from toxic Microcystis cyanobacteria blooms, which first appeared significantly in 2009.

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