Mexico’s cenotes are among the planet’s most dramatic natural geological formations, offering visitors a rare chance to venture beneath the Earth’s surface into a fascinating and seldom seen underwater world. Scuba divers exploring these sunken realms can expect spectacular scenery, fascinating archaeological finds, bizarre visual effects, and an aura of mystery - as these caves were considered sacred to the indigenous people of the Yucatan and believed to be entries to the Mayan underworld of Xibalba. These otherworldly dive sites lie scattered across the Yucatan Peninsula and come in every shape, size, and depth. In fact, there’s a cenote to suit every diver, regardless of certification and skill level.
Read on to learn all that you need to know before taking the plunge in these incredible caverns and caves!
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What are cenotes, and how did they form?
Mexico’s famous cenotes are naturally formed flooded sinkholes found throughout the Yucatan Peninsula. These fascinating geological features are created when limestone bedrock is dissolved away by rain water slowly percolating down through cracks, eventually creating a cavernous space within the rock. Unsupported, the ceiling then collapses leaving the circular sinkhole open to the surface. Many cenotes begin with one large primary chamber, which then branches off into vast cave systems that can venture several kilometres horizontally underground. Some of these eventually lead to the ocean, while others become more and more narrow, disappearing into a series of small and impassible channels.
The ongoing processes of karstification, in which the limestone is dissolved and recrystallized once again, creates the dramatic formations seen in caves of all kinds - including cenotes. Many of these underground systems feature massive crystals and suspended stones, walls that seem to melt, stalactites, and stalagmites. And in cenotes that eventually meet the ocean, divers can witness a bizarre visual effect known as a halocline. This seemingly oily mix of fresh and saltwater swirls and changes as divers swim past, producing a dizzying and dazzling show made entirely of H2O.
Mexico’s cenotes developed during the last ice age when sea levels were much lower. This left limestone bedrock and coral reefs exposed to air, creating the perfect conditions for the creation of sinkholes - and shelter for species of animal alive during this period. Then, when the ice age ended, and the planet’s polar ice caps melted again, sea levels rose, flooding the cenotes. In more modern times, the caves and caverns where used by the ancient Mayan - and this is why Mexico’s cenotes are well known for their fossils and artefacts that date back thousands of years. Often lost to the jungle and undisturbed for millennia, these underwater galleries now lend valuable insight into how the Yucatan Peninsula’s land and sea have evolved and changed.
Why Mexico’s Yucatan Peninsula has so many caves
The formation of Mexico’s Yucatan Peninsula began more than 65 million years ago when the entire area was covered by the ocean. A massive meteor strike in the Gulf of Mexico changed the region’s topography and geology, depositing large amounts of limestone sediment that formed layers, eventually building up enough soil to create a peninsula.
Caves and cenotes can only develop in heavily mineralised stone and sediment. And, while all that limestone deposited by the meteor does little for farming or agriculture, it supports a vast jungle ecosystem and creates the perfect conditions for subterranean caverns to form. Cenotes are scattered throughout the Yucatan Peninsula. However, a high-density circular formation of caverns and caves lines the crater rim left behind by the Chicxulub impact. This circular area has the highest concentration of limestone, allowing it to form the region’s most dramatic subterranean systems.
Since the meteor impact, the Yucatan Peninsula has emerged and has submerged several times. This caused degradation and erosion, allowing many underground caves to become flooded and then dry out repeatedly.
The Chicxulub meteor impact and death of the dinosaurs
The Yucatan peninsula is basically a flat piece of limestone, formed in a shallow seabed over millions of years. As tectonic plates shifted and sea levels dropped, this vast slab of rock was raised above the surface of the ocean, exposing the limestone to the eroding rain and creating the perfect conditions for the creation of cenotes. But this isn’t the complete story.
Sinkholes and karst landscapes are found around the world - in fact pretty much anywhere where limestone has been raised above sea level. But the Yucatan is unique simply because of the sheer number of cenotes - there are over 7,000 of them! So what makes the Yucatan so different?
When viewed on a map, over 900 of the cenotes are found in a ring that runs south near the city of Merida. In fact, this ‘Ring of Cenotes’ marks the rim of the famous Chicxulub crater - the impact site of the meteor that wiped out the dinosaurs, along with much of the life on earth over 66 million years ago. The vast amount of energy released by this impact event - equivalent to 100 trillion tons of TNT - shattered and reformed the deep continental rock around the impact site and farther into the peninsula, creating a vast impermeable mass. The impact crater itself is buried too deeply by new limestone laid down since the event to directly influence the creation of sinkholes in more modern times. Instead it is thought that the flow of water through the limestone peninsula is diverted away by the impermeable rock, creating the ideal environment for the creation of sinkholes in a ring that marks the rim of the crater, and further into the Yucatan peninsula.
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Mayan culture and its ties to the cenotes
The Yucatan Peninsula was once ruled by the Maya, an ancient farming civilisation who built a vast network of cities and settlements. Because the region has almost no rivers and only a few lakes, the Maya relied on cenotes as the only perennial source of freshwater. This is why the most impressive Mayan cities, including the famous Chichen Itza, were built close to these natural wells. Even the name cenote has its roots in Mayan culture, having been derived from the indigenous name ts’ono’ot or d’zonot, which means “water tank”.
Because the Maya believed cenotes were gateways to the afterlife, they also frequently performed rites and rituals in and around them, usually as tributes to the rain god Chaac. In some cases, this included throwing valuable items into their depths. Human and animal sacrifices may also have been performed in the cenotes, as a number of skulls and other skeletal remains, as well as sacrificial tools, have been found within them.
Today, modern Mayan communities still consider the cenotes sacred, performing less violent rituals around them. Divers who want to learn more about the ancient practices that took place here can visit sites like Sacred Cenote, where scientists have recovered jade, gold, pottery, bones, and ancient tools. Other such artefacts are housed in Mexico’s national museum of anthropology.
The best cenote diving in Mexico
Mexico’s cenotes vary greatly, with everything from barren pits to intricate cave systems packed with formations open for exploration by scuba divers. Keep in mind; you should never enter a cave or cavern system that you are not trained and certified for. And, while exploring the cenotes, you will see plenty of easy to understand signs underwater to help you stay on course. Never deviate from the designated route or dive site, as doing so can lead to an underwater emergency.
This fantastic multilevel dive once claimed the region’s most difficult entry, with divers trekking through the jungle before lowering their equipment into the cavern with ropes. Today, a dirt road has made access far easier, opening the site to more divers. You’ll descend straight down into a massive cylindrical chamber with a maximum depth below 100-metres. Drop through a mysterious milky white cloud of hydrogen sulfide, and begin a slow multi-level ascent touring the chamber’s near-vertical walls on your way up. Massive rings show where the cave system’s water level rose and fell during various ice ages, and the sunlight from the jungle above creates a stunning effect with beams of light penetrating beyond 30 metres.
- Best for - Deep exploration
Named for its two central caverns connected by a maze of narrow cave systems, this site does look a bit like two eyes staring up from the jungle. Two different dives can be done here, both starting and ending at the same place but exploring different areas along the way. The Barbie Line is a 500-metre long circuit, leading divers around the opening of the second eye. This route offers plenty of daylight and leads through a spacious chamber with towering columns and stalactites. The Bat Cave Line is the darker and more challenging of the two routes, leading around an air-filled dome with little natural light entering. Divers can ascend inside the dome to see fragile and fascinating cave formations as well as a colony of bats living inside. Certified cave divers may explore beyond these initial areas, but only with proper guiding and gear.
- Best for - Fascinating underwater formations
Easily the Yucatan’s most photographed cenote, this dive site is magical, mysterious, and even a bit spooky. Descend in this sinkhole’s main chamber, eventually passing through a swirling two-metre thick layer of hydrogen sulfide found at around 30-metres, formed by decomposing vegetation. This barrier separates the cenote’s top layer of fresh water from the saltwater below. Out of this opaque artificial seeming surface rises the top of the collapsed cave ceiling and massive petrified trees and root structures that came down with it. These formations look a bit like an island with trees growing up out of it. During your ascent, you can tour a small cavern loop, view the cavern’s single large stalagmite, and enjoy a look upward into the jungle, with a reflection of the trees above.
- Best for - Underwater photography
This site’s two entry points lead into the same room yet offer surprisingly different scenery along the way. The first chamber is relatively large, with light entering from the jungle-clad opening. Pass into the second room, where a portion of the ceiling has collapsed under an air dome. Divers can surface here for an opportunity to admire two levels of beautiful stalactites. Along the opening of the cavern’s main entrance, trunks and branches reach down into the water from the forest above, creating a dazzling light show. Chac Mool has a famously strong halocline, with salt and freshwater mixing, creating fascinating visual effects. It is also one of the easiest cenotes to explore, with large open chambers and a maximum depth of 12 metres. More challenging penetration routes are available to certified cavern divers, allowing visitors to glimpse the largest underwater stalactite in the world.
- Best for - Beginners
This shallow cenote is open to divers and snorkellers alike, with much of the system offering maximum depths of less than 10-metres. Named for the number of animal skeletons found in the cavern system, this is one of the Yucatan Peninsula’s most archaeologically interesting sites, with artefacts including the nearly complete fossilised remains of an extinct prehistoric camel. This cenote also belongs to the second-longest underwater cave system in the world, Cenotes Sac Aktun. Much of Pet Cemetery is spacious and well lit, making it easy to enjoy its intricate decorations, including delicate white stalactites and stalagmites, and column formations. The site’s amazing water clarity enhances the effect, giving many of its chambers the look of crystal palaces.
- Best for - Archaeological interest
Two dive sites in one, Tajma Ha offers spectacular underwater sights with a sharp halocline, dazzling light effects, beautiful fossils, and giant limestone halls. Visitors can also tour chambers scattered with rubble from ceiling collapses, surface in air-filled domes full of bats, visit rooms tinged yellow with tannic acid, and witness astonishing formations - with incredibly delicate columns, stalactites, and stalagmites. Both routes at this cenote are recommended for experienced divers, as their up and down profiles are a bit aggressive for beginners and people with sensitive ears. Certified cavern and divers can pass into seldom seen chambers of this system, including the Chinese Garden, where delicate formations line the ceiling, floor, and walls.
- Best for - Advanced and experienced divers
Garden of Eden
This spectacular cenote begins as a pond with crystal clear water full of plant life and fish. Other animals like freshwater shrimp, eels, and turtles can also be seen close to the surface, making it a popular spot for both divers and snorkellers. This large, open area is also a fantastic training ground for cavern and cave certification practice. Head into the cavern system to see moss-lined pools and a thick halocline at about 12 meters. Explorers will also pass an area known as the Cenote Coral Garden, where crystalised formations resemble an underground reef. The Garden of Eden is also home to a strong halocline, with a stark difference in temperature delivering a surprising chill.
- Best for - Cave and cavern diving students
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