The Chicxulub crater
Sixty-six million years ago, a ten-kilometre asteroid slammed into Yucatan’s shallow carbonate sea. No bowl is visible at the surface today, but the shockwave shattered deep bedrock, defining the peninsula’s underground drainage and the arc of cenotes we swim in today.
The physics of the impact: 66 million years ago
At the end of the Cretaceous period, a rocky asteroid between 10 and 14 kilometres wide collided with the shallow continental shelf of present-day Yucatan at an estimated speed of 20 kilometres per second (over 70,000 km/h). Striking obliquely at an angle of roughly 60 degrees, the bolide pierced through coastal waters and shattered deep continental basement granite.
The energy released equalled billions of atomic bombs of Hiroshima magnitude. In fractions of a minute, it excavated a transient crater cavity nearly 30 kilometres deep and 100 kilometres across. Seconds later, deep crustal rock rebounded vertically like a liquid droplet in water, collapsing outwards to form a multi-ring basin 180 kilometres wide.
The target rocks proved critical: the asteroid slammed into thick beds of marine limestone and anhydrite (calcium sulphate). The vaporised evaporite released tens of billions of tons of sulphate aerosols, soot and microscopic dust into the upper stratosphere. This opaque shroud blocked sunlight for years, halting photosynthesis, causing severe acid rain and triggering global cooling in what science classifies as the Cretaceous-Paleogene (K-Pg) mass extinction. Approximately 75% of all plant and animal species on Earth, including all non-avian dinosaurs, died out during this ecological collapse.
How it was discovered: from oil drilling to the Nobel Prize
Uncovering Chicxulub ranks among science's greatest detective stories. In 1978, geophysicists Antonio Camargo and Glen Penfield conducted airborne geomagnetic surveys for state oil company Pemex across the Gulf of Mexico. They detected an enormous circular anomaly beneath coastal waters completed on land by concentric gravity lows. Deemed devoid of commercial oil deposits, the data remained filed in corporate archives.
Simultaneously in 1980, Nobel laureate physicist Luis Alvarez and his geologist son Walter Alvarez discovered a razor-thin layer of clay in Italy and Denmark rich in iridium — an element extremely rare in Earth's crust but abundant in asteroids — precisely at the Cretaceous-Tertiary boundary. Geologists worldwide launched a search for the missing impact crater.
In 1991, Canadian geologist Alan Hildebrand tracked down the forgotten Pemex records and acquired core samples from old drill holes near Chicxulub Puerto. Microscopic analysis revealed shocked quartz with distinctive intersecting planar deformation features and glassy melt tectites. The catastrophic ground zero had finally been pinned down.
The Ring of Cenotes: the visible surface scar
The reason Chicxulub captivates travelers exploring Yucatan today is the Ring of Cenotes. Following the impact, during the Tertiary and Quaternary epochs, shallow tropical seas laid down hundreds of metres of fresh limestone layers, burying the crater completely flat.
However, the outer boundaries of the buried crater formed deep concentric fault zones where the stone remained pulverized, fractured and far more permeable than the surrounding bedrock. Millennia later, when sea levels dropped and the platform emerged, rainfall rich in atmospheric carbon dioxide began dissolving surface limestone.
Karst dissolution accelerated along these buried fault weaknesses, causing subterranean cave ceilings to collapse into a nearly perfect semicircular arc of hundreds of cenotes that maps the crater perimeter at the surface. Most of Yucatan’s deepest, clearest sinkholes — including those around Homun, Cuzama and Tecoh — belong to this geological ring.
Chronology of the impact and current topography
| Geological Phase | Estimated Era | Physical Occurrence | Visible Consequence Today |
|---|---|---|---|
| Impact & collapse | 66 million years ago | Asteroid vaporises rock, carving a 180 km multi-ring basin | Deep gravitational field anomalies detected by satellite |
| Marine sedimentation | 66 to 2.5 million years ago | Warm oceans bury the depression with thick carbonate sediments | Completely flat, riverless terrain throughout Yucatan |
| Quaternary karst dissolution | 2.5 million years ago to present | Acidic rainwater preferentially dissolves rock along ring faults | Formation of the semicircular Ring of Cenotes |
| Maya human settlement | 3,000 years before present | Maya builders erect towns beside the sinkholes of the ring | Ancient cities and colonial haciendas clustering along the arc |
What you can actually visit today
With no exposed volcanic caldera to look down into, travel focuses on the hydrological consequences of the impact:
- Swimming in Ring Cenotes: this is the most tangible encounter with the disaster. Swimming in the cavern pools of Homun or Cuzama places you directly inside the bedrock fracture zone created 66 million years ago. We detail cave types in our guide to what is a cenote.
- The Meteorite Museum in Progreso: situated on the seaside malecón of Progreso, this modern science museum presents dinosaur recreations, geological core exhibits and interactive physics displays explaining the impact.
- Chicxulub Puerto: a relaxed fishing village with colourful fishing skiffs and quiet beaches. While it has no giant monument, standing in its small central plaza places you at the epicenter where Earth's evolutionary history changed course.
To discover the wildlife that replaced prehistoric reptiles across coastal lagoons, browse our overview of Yucatan wildlife and coastal Yucatan mangroves.
Our full-day itineraries visit several of the most spectacular cenotes situated along the geological arc of the crater. The most direct way is the Santa Bárbara cenotes tour in Homún; every other departure is in our tour catalogue.
Frequently asked questions
Can you see the Chicxulub crater at the surface?
No. The crater structure is completely buried under 300 to 1,000 metres of younger marine limestone laid down over the past 66 million years. There is no visible crater basin on the landscape.
How is the dinosaur asteroid connected to Yucatan’s cenotes?
The impact deeply fractured the bedrock along concentric fault lines. Millions of years later, acidic rainwater dissolved the limestone faster along these fractures, carving the Ring of Cenotes.
How large was the asteroid that struck Yucatan?
It measured between 10 and 14 kilometres in diameter and struck at an estimated speed of 20 kilometres per second into the shallow coastal shelf.
Where is Chicxulub Puerto located?
It is a seaside fishing town located along Yucatan’s northern coast, roughly 8 kilometres east of Progreso and a 45-minute drive north from downtown Merida.
What scientific evidence proved the impact occurred here?
A worldwide sedimentary layer containing rare extraterrestrial iridium, circular gravity field anomalies from Pemex surveys, and drill core samples containing shocked quartz and impact-melt rocks.
Why did this specific impact cause the extinction of the dinosaurs?
The asteroid vaporised sulphate-rich marine evaporites, ejecting billions of tons of sulphur and dust that blocked sunlight for years, halting photosynthesis and collapsing global food webs.
What visitor attraction in Progreso covers the impact?
The Meteorite Museum (Museo del Meteorito) on the Progreso beachfront, a modern science centre featuring dinosaur fossil casts, interactive displays and geological exhibits.
Are the cenotes in Homun and Cuzama part of the crater ring?
Yes. Homun, Cuzama and Tecoh sit directly on the semicircular arc of the Ring of Cenotes, representing one of the highest concentrations of pristine karst sinkholes in the Americas.
What is a cenote · The wildlife of Yucatan · What is a mangrove · When to visit Yucatan · Yucatan guides
Want to swim inside the Ring of Cenotes?
Our excursions visit the most breathtaking sinkholes aligned along the geological rim of the crater.